chore(block-scheduler): add scheduler grpc methods to auth mw ignore list

[ashwanthgoli]

What this PR does / why we need it

By default loki applies user header interceptor middleware for all grpc methods on the server side which tries to extract user information from grpc metadata. But block scheduler methods are internal and their functionality is not tied to a single user. Adding the scheduler methods to the ignore list to not fail in the interceptor.

Similarly grpcclient.Instrument() tries to extract user information from context to perform per-tenant instrumentation cauing these methods to fail. Updated the Dial opts to only include the required interceptors.

Which issue(s) this PR fixes:

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[cyriltovena]

LGTM