🌱 Remove test/e2e/Makefile and move targets to root Makefile

[oscr]

What this PR does / why we need it:
Removes test/e2e/Makefile and moves targets to the root Makefile.

The root Makefile now has the following last section:

end-to-end
  cluster-templates                              Generate cluster templates for all versions
  cluster-templates-v1alpha3                     Generate cluster templates for v1alpha3
  cluster-templates-v1alpha4                     Generate cluster templates for v1alpha4
  cluster-templates-v1beta1                      Generate cluster templates for v1beta1
  test-extension-deployment                      Generate deployment for test extension
  run                                            Run the end-to-end tests

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #7320

[fabriziopandini]

@oscr thanks for jumping on this one

[fabriziopandini]

great work
/lgtm

@sbueringer PTAL when you have some time

[oscr]

Thank you for all your feedback and help @fabriziopandini 🙏

[sbueringer]

I'll take a look soon, probably tomorrow

[sbueringer]

just nits

[sbueringer]

Can we merge #7288 before #7329? I think #7329 is easier to rebase

[oscr]

Can we merge #7288 before #7329? I think #7329 is easier to rebase

Sure, that's no issue for me. I can rebase the pr as soon as #7288 merges.

[oscr]

/retest

[sbueringer]

/test pull-cluster-api-e2e-full-main

/lgtm

EDIT: I think Prow has some problems right now. If it doesn't re-act let's wait a bit or retest tomorrow

[oscr]

Yes, Prow seems really slow to trigger today.

[fabriziopandini]

#7288 is merged
/lgtm

@sbueringer for final approval

[fabriziopandini]

(oops it is already there)
/approve

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