fix: property endpoint is ignored when using instrumentation_key (#34399)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->

Fixing a bug

**Link to tracking Issue:**  #33971 

**Testing:** It's just one line and simple, so I just tested locally. If
test cases needed, I can provide in this PR.

**Documentation:** if no connection string and endpoint is provided,
then use it instead of the default one.

---------

Co-authored-by: David Ashpole <[email protected]>

Author: hgaol

.chloggen/azuremonitorexporter-ignore-endpoint.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: azuremonitorexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: fix issue for property endpoint is ignored when using instrumentation_key
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33971]
+
+# (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/azuremonitorexporter/connection_string_parser.go

@@ -44,7 +44,11 @@ func parseConnectionString(exporterConfig *Config) (*ConnectionVars, error) {
 	}
 	if connectionString == "" {
 		connectionVars.InstrumentationKey = instrumentationKey
-		connectionVars.IngestionURL = getIngestionURL(DefaultIngestionEndpoint)
+		if exporterConfig.Endpoint == "" {
+			connectionVars.IngestionURL = getIngestionURL(DefaultIngestionEndpoint)
+		} else {
+			connectionVars.IngestionURL = getIngestionURL(exporterConfig.Endpoint)
+		}
 		return connectionVars, nil
 	}