#1003 Removal of default security context UID setting

[MarkusFlorian79]

What this PR does / why we need it:

Does reapply a fix done in 1.6.0 This is the text form ./kong/UPGRADE.md:

Removal of default security context UID setting

Versions of Kong prior to 2.0 and Kong Enterprise prior to 1.3 use Docker
images that required setting a UID via Kubernetes in some environments
(primarily OpenShift). This is no longer necessary with modern Docker images
and can cause issues depending on other environment settings, so it was
removed.

Most users should not need to take any action, but if you encounter permissions
errors when upgrading (kubectl describe pod PODNAME should contain any), you
can restore it by adding the following to your values.yaml:

securityContext:
  runAsUser: 1000


#### Which issue this PR fixes
*(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*
  - fixes #1003 

#### Special notes for your reviewer:

#### Checklist
[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]
- [ ] PR is based off the current tip of the `main` branch.
- [ ] Changes are documented under the "Unreleased" header in CHANGELOG.md
- [ ] New or modified sections of values.yaml are documented in the README.md
- [ ] Commits follow the [Kong commit message guidelines](https://github.com/Kong/kong/blob/master/CONTRIBUTING.md#commit-message-format)

[CLAassistant]

All committers have signed the CLA.

[rainest]

Closing pending further investigation into whether we can satisfy both OpenShift's and base Kubernetes' desires here: #1003 (comment)