[chore] Remove go report card badge from readme (#15559)

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#### Description
[Go Report Card](https://goreportcard.com/) has been retired. The badge
can be removed from the readme.

Matches the removal in contrib
open-telemetry/opentelemetry-collector-contrib#49538

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#### Authorship

- [x] I, a human, wrote this pull request description myself.

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Author: dyl10s

README.md

@@ -14,9 +14,6 @@
   <a href="https://github.com/open-telemetry/opentelemetry-collector/actions/workflows/build-and-test.yml?query=branch%3Amain">
     <img alt="Build Status" src="https://img.shields.io/github/actions/workflow/status/open-telemetry/opentelemetry-collector/build-and-test.yml?branch=main&style=for-the-badge">
   </a>
-  <a href="https://goreportcard.com/report/github.com/open-telemetry/opentelemetry-collector">
-    <img alt="Go Report Card" src="https://goreportcard.com/badge/github.com/open-telemetry/opentelemetry-collector?style=for-the-badge">
-  </a>
   <a href="https://codecov.io/gh/open-telemetry/opentelemetry-collector/branch/main/">
     <img alt="Codecov Status" src="https://img.shields.io/codecov/c/github/open-telemetry/opentelemetry-collector?style=for-the-badge">
   </a>