[exporter/prometheusremotewrite] fix/sanitize exponential retry defaults (open-telemetry#30286)

**Description:** 

This PR sanitizes the default retry settings by using default
constructor and setting the single `InitialInterval`, instead of user
initializing entire structure manually.

The current default settings do not become exponential due to being
upper bound at 200ms by `MaxInterval: 200 * time.Millisecond,`. This
effectively caps the wait intervals between requests at a very low
interval, thus becomes more of a linear retry than exponential. And due
to the distributed nature of the Otel Collector, coupled with each
metric export being handled by go-routine, this caused a massive churn
of requests when remote endpoint is unavailable.

*Before/Current*

```
first backoff 673.174543ms 

elapsed 83ns
next backoff 25.476545ms 

elapsed 44.95825ms
next backoff 134.374813ms 

elapsed 217.756375ms
next backoff 120.396777ms 

elapsed 475.136125ms
next backoff 130.842218ms 

elapsed 607.402958ms
next backoff 170.769874ms 

elapsed 836.674125ms
next backoff 201.503411ms 

elapsed 938.644667ms
next backoff 166.184906ms 

elapsed 1.186788375s
next backoff 143.509999ms 

elapsed 1.296595125s
next backoff 190.37078ms 

.
.
.

elapsed 59.34433225s
next backoff 298.715693ms 

elapsed 59.533727458s
next backoff 136.844597ms 

total requests made: 299
```

*After this change*
```
first backoff 343.109367ms 

elapsed 166ns
next backoff 55.833932ms 

elapsed 74.545375ms
next backoff 151.276125ms 

elapsed 192.138833ms
next backoff 364.656003ms 

elapsed 744.091666ms
next backoff 564.927763ms 

elapsed 1.75722475s
next backoff 1.248209052s 

elapsed 4.077209583s
next backoff 3.374196626s 

elapsed 8.769952708s
next backoff 8.449184533s 

elapsed 23.303548708s
next backoff 7.341400254s 

elapsed 43.388838083s
next backoff 22.327511322s 

elapsed 1m14.147837833s
next backoff 43.127363668s 

elapsed 1m55.730420666s
next backoff 34.674349715s 

elapsed 2m16.703792375s
next backoff 40.140627107s 

elapsed 2m31.856713458s
next backoff 27.45308936s 

elapsed 2m49.376459416s
next backoff 29.853555518s 

elapsed 3m14.625332666s
next backoff 17.209739491s 

elapsed 3m37.914321833s
next backoff 15.614405319s 

elapsed 4m14.614882458s
next backoff 35.458886397s 

elapsed 4m33.424847s
next backoff -1ns 

total requests made: 18
```

**Link to tracking Issue:**
No issues opened from my side.

**Testing:** 
Unit testes already in place.

**Documentation:**
N/A

Author: bmiguel-teixeira

.chloggen/prometheusremotewrite_sanitize_retry_defaults.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: prometheusremotewriteexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: sanitize retry default settings
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [30286]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

exporter/prometheusremotewriteexporter/factory.go

@@ -8,7 +8,6 @@ import (
 	"errors"
 	"time"
 
-	"github.com/cenkalti/backoff/v4"
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/confighttp"
 	"go.opentelemetry.io/collector/config/configopaque"
@@ -67,19 +66,15 @@ func createMetricsExporter(ctx context.Context, set exporter.CreateSettings,
 }
 
 func createDefaultConfig() component.Config {
+	retrySettings := exporterhelper.NewDefaultRetrySettings()
+	retrySettings.InitialInterval = 50 * time.Millisecond
+
 	return &Config{
 		Namespace:         "",
 		ExternalLabels:    map[string]string{},
 		MaxBatchSizeBytes: 3000000,
 		TimeoutSettings:   exporterhelper.NewDefaultTimeoutSettings(),
-		RetrySettings: exporterhelper.RetrySettings{
-			Enabled:             true,
-			InitialInterval:     50 * time.Millisecond,
-			MaxInterval:         200 * time.Millisecond,
-			MaxElapsedTime:      1 * time.Minute,
-			RandomizationFactor: backoff.DefaultRandomizationFactor,
-			Multiplier:          backoff.DefaultMultiplier,
-		},
+		RetrySettings:     retrySettings,
 		AddMetricSuffixes: true,
 		SendMetadata:      false,
 		HTTPClientSettings: confighttp.HTTPClientSettings{