Fix the namespace acceptance tests

[ramya-bangera]

Provider configuration has the wrong provider name as "tmc" instead of "tanzu-mission-control" causing the tests to fail. Modified the test to use the common provider testing code instead of the incorrect one.

1. What this PR does / why we need it:
   Fixes the failing namespace acceptance tests

2. Which issue(s) this PR fixes

    (optional, in `fixes #<issue number>` format, will close the issue(s) when PR gets merged):
   
    Fixes issue tracked in internal Jira
   

3. Additional information

4. Special notes for your reviewer

namespace % go test -v -tags=namespace                                     
=== RUN   TestAcceptanceForNamespaceDataSource
TMC resources applied to the cluster successfully
 data_source_namespace_test.go:53: namespace data source acceptance test complete!
--- PASS: TestAcceptanceForNamespaceDataSource (301.15s)
.......
TMC resources applied to the cluster successfully
 resource_namepace_test.go:49: namespace resource acceptance test complete!
--- PASS: TestAcceptanceForNamespaceResource (279.15s)

[shobha2626]

LGTM

[github-actions]

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