Revert "Use action/checkout fetch-depth instead of manually fetch (#4535)"

[jpkrohling]

This reverts commit 5405247.

The problem is happening because there's a mismatch between references: previously, the changelog was obtaining the latest commit from github.base_ref, which is typically main. The referenced commit uses the GitHub Action, which will get the latest commit from the PR itself. Running a diff between the PR against itself yields no results at all:

$ git fetch origin jpkrohling/issue4556 --depth=1
remote: Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
From github.com:jpkrohling/opentelemetry-collector
 * branch              jpkrohling/issue4556 -> FETCH_HEAD

$ git diff --name-only FETCH_HEAD
$

Whereas running the same command using main in the FETCH_HEAD yields

$ git fetch origin main --depth=1
remote: Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
From github.com:jpkrohling/opentelemetry-collector
 * branch              main       -> FETCH_HEAD

$ git diff --name-only FETCH_HEAD
CHANGELOG.md
config/configauth/configauth_test.go
config/configauth/default_serverauthenticator.go
config/configauth/default_serverauthenticator_test.go
config/configauth/mock_serverauth.go
config/configauth/mock_serverauth_test.go
config/configgrpc/configgrpc_test.go
config/confighttp/confighttp_test.go

Fixes #4559

[codecov]

Codecov Report

Merging #4560 (cfedf11) into main (5514ecb) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #4560   +/-   ##
=======================================
  Coverage   90.50%   90.50%           
=======================================
  Files         180      180           
  Lines       10545    10545           
=======================================
  Hits         9544     9544           
  Misses        782      782           
  Partials      219      219           

---

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[jpkrohling]

According to the documentation, fetch-depth: 1 is already the default, so, this is a noop. https://github.com/actions/checkout#usage