Allow Settings API with OAuth credentials

[tomazpu]

What this PR does / Why we need it:

This PR removes the validation check for Settings API in download and deploy to fail if Token is not set. This allows to use OAuth credentials with Settings API.

Special notes for your reviewer:

Does this PR introduce a user-facing change?

[github-actions[bot]]

Unit Test Results

1 893 tests  +2   1 892 ✅ +2   54s ⏱️ ±0s   133 suites ±0       1 💤 ±0      1 files   ±0       0 ❌ ±0 

Results for commit 5e3a60ce. ± Comparison against base commit 3ca846a5.

:recycle: This comment has been updated with latest results.

[github-actions[bot]]

E2E Test Results

    4 files   -   1    268 suites   - 133   26m 19s ⏱️ - 43m 24s 2 011 tests ±  0  2 009 ✅ ±  0  2 💤 ±0  0 ❌ ±0  2 126 runs   - 115  2 124 ✅  - 115  2 💤 ±0  0 ❌ ±0 

Results for commit 5e3a60ce. ± Comparison against base commit 3ca846a5.

This pull request removes 2 and adds 2 tests. Note that renamed tests count towards both.

``` github.com/dynatrace/dynatrace-configuration-as-code/v2/cmd/monaco/integrationtest/v2 ‑ TestPaginationClassic github.com/dynatrace/dynatrace-configuration-as-code/v2/cmd/monaco/integrationtest/v2 ‑ TestPaginationPlatform ``` ``` github.com/dynatrace/dynatrace-configuration-as-code/v2/cmd/monaco/deploy ‑ Test_ValidateAuthenticationWithProjectConfigs/OAuth_manifest_with_settings_api github.com/dynatrace/dynatrace-configuration-as-code/v2/cmd/monaco/download ‑ TestDownloadConfigs_OnlySettings ```

:recycle: This comment has been updated with latest results.