[service] fix proctelemetry registration bug (#11093)

This bug caused proctelemetry metrics to not be registered if a user
configured the Collector's internal telemetry via `readers` only and
disabled `address`. The check in the `if` statement is no longer needed
since a no-op meter provider will be configured unless the telemetry
level is set.

Mentioned in #10919

---------

Signed-off-by: Alex Boten <[email protected]>

Author: codeboten

.chloggen/codeboten_fix-bug.yaml

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+# 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. otlpreceiver)
+component: service
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Ensure process telemetry is registered when internal telemetry is configured with readers instead of an address.
+
+# One or more tracking issues or pull requests related to the change
+issues: [11093]
+
+# (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:
+
+# 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: []