Remove extensions related yamls from v1.3

[waodim]

Description

NOTE: This is a PR from a series of PRs that will follow that deal with the removal of v1beta3 from operator v1.3.

In this PR I removed .yaml files that were related to the extensions.

https://dt-rnd.atlassian.net/browse/K8S-11056

How can this be tested?

Helm unittests should run through, double check if I missed something.

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 64.88%. Comparing base (5502720) to head (f4ee594). Report is 1 commits behind head on release-1.3.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-1.3 #3696 +/- ## ============================================ Coverage 64.88% 64.88% ============================================ Files 386 386 Lines 21117 21117 ============================================ Hits 13702 13702 Misses 6098 6098 Partials 1317 1317 ``` | [Flag](https://app.codecov.io/gh/Dynatrace/dynatrace-operator/pull/3696/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Dynatrace) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/Dynatrace/dynatrace-operator/pull/3696/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Dynatrace) | `64.88% <ø> (ø)` | | 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=Dynatrace#carryforward-flags-in-the-pull-request-comment) to find out more.

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[0sewa0]

in config/helm/chart/default/templates/_labels.tpl remove

{{/*
Extensions Controller (EEC) labels
*/}}
{{- define "dynatrace-operator.extensionsControllerLabels" -}}
{{ include "dynatrace-operator.commonLabels" . }}
app.kubernetes.io/component: dynatrace-extensions-controller
{{- end -}}

{{/*
Extensions OpenTelemetry Collector (OTelC) labels
*/}}
{{- define "dynatrace-operator.extensionsOpenTelemetryCollectorLabels" -}}
{{ include "dynatrace-operator.commonLabels" . }}
app.kubernetes.io/component: dynatrace-extensions-collector
{{- end -}}