[Enterprise Search] Remove GitHub connector and GCS native

[sphilipse]

Summary

This removes the GitHub connector (which is not ready yet) and moves the Google Cloud Storage connector to non-native.

[kibana-ci]

:green_heart: Build Succeeded

• Buildkite Build
• Commit: 2748803cca4158851b32489e890da3dba1e22eb6

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
enterpriseSearch	2.5MB	2.5MB	-244.0B

Unknown metric groups

#### ESLint disabled line counts | id | [before](https://github.com/elastic/kibana/commit/a792697f412c588cb42d9c9e46c9dffd603e2e09) | [after](https://github.com/elastic/kibana/commit/2748803cca4158851b32489e890da3dba1e22eb6) | diff | | --- | --- | --- | --- | | `enterpriseSearch` | 14 | 16 | +2 | | `securitySolution` | 408 | 412 | +4 | | total | | | +6 | #### Total ESLint disabled count | id | [before](https://github.com/elastic/kibana/commit/a792697f412c588cb42d9c9e46c9dffd603e2e09) | [after](https://github.com/elastic/kibana/commit/2748803cca4158851b32489e890da3dba1e22eb6) | diff | | --- | --- | --- | --- | | `enterpriseSearch` | 15 | 17 | +2 | | `securitySolution` | 487 | 491 | +4 | | total | | | +6 |

To update your PR or re-run it, just comment with: @elasticmachine merge upstream

[kibanamachine]

💚 All backports created successfully

Status	Branch	Result
✅	8.9

Note: Successful backport PRs will be merged automatically after passing CI.

Questions ?

Please refer to the Backport tool documentation

[kibanamachine]

Looks like this PR has a backport PR but it still hasn't been merged. Please merge it ASAP to keep the branches relatively in sync.

[kibanamachine]

Looks like this PR has a backport PR but it still hasn't been merged. Please merge it ASAP to keep the branches relatively in sync.

[kibanamachine]

Looks like this PR has a backport PR but it still hasn't been merged. Please merge it ASAP to keep the branches relatively in sync.