Add oauth-proxy to monolithic

[rubenvp8510]

Fixes https://github.com/grafana/tempo-operator/issues/922

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 79.10448% with 28 lines in your changes are missing coverage. Please review.

Project coverage is 76.43%. Comparing base (9e199b2) to head (355dc1f).

Files	Patch %	Lines
internal/manifests/monolithic/build.go	18.51%	22 Missing :warning:
apis/tempo/v1alpha1/tempomonolithic_defaults.go	75.00%	1 Missing and 2 partials :warning:
internal/manifests/oauthproxy/oauth_proxy.go	97.22%	1 Missing and 1 partial :warning:
internal/manifests/queryfrontend/query_frontend.go	93.75%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #921 +/- ## ========================================== + Coverage 76.40% 76.43% +0.02% ========================================== Files 94 94 Lines 6011 6069 +58 ========================================== + Hits 4593 4639 +46 - Misses 1145 1159 +14 + Partials 273 271 -2 ``` | [Flag](https://app.codecov.io/gh/grafana/tempo-operator/pull/921/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=grafana) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/grafana/tempo-operator/pull/921/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=grafana) | `76.43% <79.10%> (+0.02%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=grafana#carryforward-flags-in-the-pull-request-comment) to find out more.

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[andreasgerstmayr]

Looks good! I left a few minor comments.