Build: don't run release builds on grafana/grafana repo

[malcolmholmes]

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

[dsotirakis]

LGTM.

Let's try it and rollback the changes if needed

[grafanabot]

The backport to v8.2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-42785-to-v8.2.x origin/v8.2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x b6818718e9983fffd3351f4ab1545baba0e2b26f
# Push it to GitHub
git push --set-upstream origin backport-42785-to-v8.2.x
git switch main
# Remove the local backport branch
git branch -D backport-42785-to-v8.2.x

Then, create a pull request where the base branch is v8.2.x and the compare/head branch is backport-42785-to-v8.2.x.

[grafanabot]

The backport to v8.3.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-42785-to-v8.3.x origin/v8.3.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x b6818718e9983fffd3351f4ab1545baba0e2b26f
# Push it to GitHub
git push --set-upstream origin backport-42785-to-v8.3.x
git switch main
# Remove the local backport branch
git branch -D backport-42785-to-v8.3.x

Then, create a pull request where the base branch is v8.3.x and the compare/head branch is backport-42785-to-v8.3.x.