frontend: test: Fix mocker namespace interpolation

[ahmad-kashkoush]

Summary

This PR fixes a silent bug in generateK8sResourceList where {{i}} placeholders
in metadata.namespace were never replaced, and adds unit tests for the function
to prevent regressions.

Related Issue

Fixes #6474

Changes

• Fixed frontend/src/test/mocker.ts: assigned the .replace() result back so
  {{i}} in metadata.namespace is actually interpolated
• Added frontend/src/test/mocker.test.ts: 4 unit tests covering {{i}}
  interpolation in metadata.name, {{i}} interpolation in metadata.namespace,
  absence of literal {{i}} in output, and the numResults option

Steps to Test

1. cd frontend && npx vitest run src/test/mocker.test.ts
2. Confirm all 4 tests pass
3. Optionally call generateK8sResourceList with namespace: 'ns-{{i}}' in any
   existing test and verify items now get distinct namespaces (ns-0, ns-1, …)
   instead of the literal ns-{{i}}

Notes for the Reviewer

• The test file requires two vi.mock calls at the top to break a
  mocker → KubeObject → util → node → KubeObject circular import; without them
  class Node extends KubeObject evaluates while KubeObject is still undefined.
• No functional changes to any component or runtime path — only the shared test
  helper is affected.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: ahmad-kashkoush / name: ahmad-kashkoush (b975799, c1eb117)

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[shivamsingh-007]

Nice catch on the missing assignment — .replace()\ returning a new string is an easy one to miss. The tests look thorough (edge cases for literal {{i}},
umResults, namespace interpolation). Also good workaround on the circular dep with the two \�i.mock\ calls. LGTM.