Replace the obsolete no-dependencies rationale in every chart helper

The doc comments on the resources and defaultedDict helpers justified the
copy-per-chart with "charts in this repo deliberately have no dependencies".
That rule fell with #214: a dependency is admissible now, just expensive, and
it sits in the README as guideline 14, not 13. The justification still holds,
but its reason is a different one - sharing the helper would mean a library
chart, a second artefact to publish, version and pull for something that
changes about once a year. searxng got that wording in PR #38; this carries it
to 21 further charts, 40 occurrences in all.

rss-bridge is deliberately left out. Its install-test fails on the Gitea
runner for a reason that predates this branch, and touching the chart would
keep it in the install-test matrix and the check red. Its copy of the sentence
is carried by #51, which has to open the chart anyway.

Comments only: every touched chart renders byte-identical against its
ci/<chart>/test-values.yaml. Each published chart takes a patch bump,
appVersion and +up suffix untouched; template-chart is never published and
takes none, but is corrected because every new chart inherits from it.

Two repo files carried the same claim at no version cost:
validate-charts.yml explained the all-charts quantity render test with it, and
change-app-version.yml still counted nine images for freesailarr - MediathekArr
made it ten.

matrix-synapse/Chart.yaml

@@ -3,7 +3,7 @@ name: matrix-synapse
 description: A Helm chart to deploy a Matrix Synapse server on Kubernetes
 icon: https://raw.githubusercontent.com/element-hq/synapse/develop/docs/favicon.png
 type: application
-version: 7.1.0+upv1.159.0
+version: 7.1.1+upv1.159.0
 appVersion: "v1.159.0"
 maintainers:
   - name: jklein