feat: upgrade Helm version to v3.20.0 and v4.1.0 (#2373)

* feat: upgrade Helm version to v3.20.0 and v4.1.0

This commit updates the recommended Helm version from v3.19.5/v4.0.5 to
v3.20.0/v4.1.0 across all workflows, Dockerfiles, and application constants.

Changes:
- Update CI matrix to test with Helm v3.20.0 and v4.1.0
- Update .github/workflows/Makefile HELM_VERSION to v4.1.0
- Update Dockerfiles with new version and SHA256 checksums
- Update pkg/app/init.go HelmRecommendedVersion to v4.1.0
- Update go.mod helm.sh/helm/v3 to v3.20.0 and helm.sh/helm/v4 to v4.1.0

Signed-off-by: yxxhero <aiopsclub@163.com>

* fix: remove source field from e2e test helm plugin configs

Signed-off-by: yxxhero <aiopsclub@163.com>

* fix: remove source field from integration test helm plugin config

Signed-off-by: yxxhero <aiopsclub@163.com>

---------

Signed-off-by: yxxhero <aiopsclub@163.com>

test/e2e/template/helmfile/testdata/helm-plugins/add-cm1/plugin.yaml

@@ -2,7 +2,6 @@ apiVersion: v1
 type: postrenderer/v1
 name: add-cm1
 version: 0.1.0
-source: test
 runtime: subprocess
 runtimeConfig:
   platformCommand:

test/e2e/template/helmfile/testdata/helm-plugins/add-cm2/plugin.yaml

@@ -2,7 +2,6 @@ apiVersion: v1
 type: postrenderer/v1
 name: add-cm2
 version: 0.1.0
-source: test
 runtime: subprocess
 runtimeConfig:
   platformCommand:

test/integration/test-cases/postrender/input/helm-plugin-add-cm/plugin.yaml

@@ -2,7 +2,6 @@ apiVersion: v1
 type: postrenderer/v1
 name: add-cm
 version: 0.1.0
-source: test
 runtime: subprocess
 runtimeConfig:
   platformCommand: