fix(check-endpoints): update grep for providers

[haarchri]

Description of your changes

fix check-endpoints.sh when installing providers via configurations the endpoints looks like:

kubectl -n upbound-system get endpoints --no-headers                                       
crossplane-contrib-function-auto-ready   10.244.0.7:9443    17m
crossplane-contrib-function-kcl          10.244.0.8:9443    17m
crossplane-webhooks                      10.244.0.11:9443   17m
upbound-provider-aws-s3                  10.244.0.12:9443   16m
upbound-provider-family-aws              10.244.0.13:9443   17m

this part will not produce an output kubectl -n upbound-system get endpoints --no-headers | grep '^provider-' | awk '{print $1}'

Fixes #

I have:

• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

[haarchri]

@sergenyalcin can we backport to v0.13.0 release ? thanks

[sergenyalcin]

Thanks @haarchri LGTM!

[github-actions]

Successfully created backport PR #21 for release-0.13.