Backport of ci: add conditional skip for docs changes into release/1.1.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #560 to be assessed for backporting due to the inclusion of the label backport/1.1.

The below text is copied from the body of the original PR.

---

Similar to consul, skip build and tests if we're only changing docs.

This should help speed up releases and daily work quick-fixes.

❯ SKIP_CHECK_BRANCH=zalimeni/conditional-skip-ci GITHUB_OUTPUT="../GITHUB_OUTPUT" .github/scripts/check_skip_ci.sh
checking file: .changelog/100.txt
checking file: .github/scripts/check_skip_ci.sh
checking file: README.md
Changes detected in only documentation files - skipping tests and build

After adding a code change:

❯ SKIP_CHECK_BRANCH=zalimeni/conditional-skip-ci GITHUB_OUTPUT="../GITHUB_OUTPUT" .github/scripts/check_skip_ci.sh
checking file: .changelog/100.txt
checking file: .github/scripts/check_skip_ci.sh
checking file: README.md
checking file: cmd/consul-dataplane/main.go
non-skippable file changed: cmd/consul-dataplane/main.go
Changes detected in non-documentation files - will not skip tests and build

---

Overview of commits

• 63d4bac