fix(app): helm client initialisation

[JGAntunes]

What this PR does / why we need it:

Addresses a problem where we were mistakenly initialising a separate helm client with a default set of values when doing a dry run templating of the chart.

Which issue(s) this PR fixes:

https://app.shortcut.com/replicated/story/130956/unable-to-install-with-new-installer

Does this PR require a test?

Changed the chart yaml we create for tests to include a kubeVersion. In our tests we're already passing an helm client to the manager:

• embedded-cluster/api/internal/managers/app/release/template_test.go

  Lines 341 to 346 in 532e4b1

  	// Create real helm client
  	hcli, err := helm.NewClient(helm.HelmOptions{
  	HelmPath: "helm", // use the helm binary in PATH
  	K8sVersion: "v1.33.0",
  	})
  	require.NoError(t, err)

However this was unused (hence the bug). This should at least make sure that we're not using a client initialised with the default values.

Does this PR require a release note?

NONE

Does this PR require documentation?

NONE