Remove references to unused 'fullnameOverride' key

What does this MR do?

Remove references to unused 'fullnameOverride' key

Removes references to the unused 'fullnameOverride' key.
This key does not appear to be documented or used anywhere,
and the templates where it appears just extend the existing
'fullname' template.

Found during development in
https://gitlab.com/gitlab-org/charts/gitlab/-/merge_requests/3091.

Changelog: other

Webservice template originally added in !1642 (merged).

Current best guess is that this was added based on Helm recommendations/defaults:

• https://github.com/helm/helm/issues/1186
• https://github.com/helm/helm/pull/3193

Testing

Compare output between branch and master with test release name

$ git checkout remove-fullnameoverride-key

$ helm template test . > template-branch.yaml

$ git checkout master

$ helm template test . > template-master.yaml

$ diff -Iy template-master.yaml template-branch.yaml
239c239
<     chart: gitlab-runner-0.51.0
---
>     chart: gitlab-runner-0.51.1
340c340
<     chart: gitlab-runner-0.51.0
---
>     chart: gitlab-runner-0.51.1
19868c19868
<     chart: gitlab-runner-0.51.0
---
>     chart: gitlab-runner-0.51.1
20067c20067
<     chart: gitlab-runner-0.51.0
---
>     chart: gitlab-runner-0.51.1
20796c20796
<     chart: gitlab-runner-0.51.0
---
>     chart: gitlab-runner-0.51.1
20809c20809
<         chart: gitlab-runner-0.51.0
---
>         chart: gitlab-runner-0.51.1
20813c20813
<         checksum/configmap: 79d126215813a27fbb8aedd03e2bc3ae5016731581befac4aed4d07f1edfca7f
---
>         checksum/configmap: 510b0fbe96717eebb774528c797fcfc1d02a9961ccc165803c11bb20174bc4c8
24584c24584
<   name: test-webservice-test-runner-hqzbw
---
>   name: test-webservice-test-runner-ltot0
24669c24669
<   name: test-shared-secrets-1-ei2
---
>   name: test-shared-secrets-1-clt

Only differences are expected (randomly-generated values).

Compare output between branch and master with webservice release name

84c84
<   name: test-webservice-branchname-default
---
>   name: test-webservice-branchname-webservice-default
...
20283c20283
<   name: test-webservice-branchname-default
---
>   name: test-webservice-branchname-webservice-default
...
...
<   name: test-webservice-branchname-default
---
>   name: test-webservice-branchname-webservice-default
22389c22389
<           name: test-webservice-branchname
---
>           name: test-webservice-branchname-webservice
23046c23046
<   name: test-webservice-branchname-default
---
>   name: test-webservice-branchname-webservice-default
23059c23059
<     name: test-webservice-branchname-default
---
>     name: test-webservice-branchname-webservice-default
23940c23940
<   name: test-webservice-branchname-default
---
>   name: test-webservice-branchname-webservice-default
23965c23965
<               serviceName: test-webservice-branchname-default
---
>               serviceName: test-webservice-branchname-webservice-default
24584c24584
<   name: test-webservice-branchname-webservice-test-runner-yd6xv
---
>   name: test-webservice-branchname-webservice-test-runner-oeibh
...

Note that the first entry, from master, removes the -webservice suffix. The second entry, this branch, maintains it.

This test is related to the changes in !3091 (merged).

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.