tests(konnect): fix flaky KongConsumerCredential tests

[pmalek]

What this PR does / why we need it:

This fixes an issue with KongConsumerCredential* tests that was spotted in https://github.com/Kong/gateway-operator/actions/runs/11242357547/job/31255881107.

   kongconsumercredential_apikey_test.go:40: deployed new KonnectAPIAuthConfiguration test-l95dt/api-auth-config-n9qjp resource
    kongconsumercredential_apikey_test.go:41: deployed new KonnectGatewayControlPlane test-l95dt/cp-0e6fa6d2 resource
    kongconsumercredential_apikey_test.go:44: deployed test-l95dt/kongconsumer-568pg KongConsumer resource
    kongconsumercredential_apikey_test.go:65: deployed new KongCredentialAPIKey test-l95dt/api-key-qfpvs resource
    kongconsumercredential_apikey_test.go:116: Starting manager for test case TestKongConsumerCredential_APIKey
    kongconsumercredential_apikey_test.go:119: FAIL:	CreateKeyAuthWithConsumer(string,operations.CreateKeyAuthWithConsumerRequest)
        		at: [/home/runner/work/gateway-operator/gateway-operator/controller/konnect/ops/credentialapikey_mock.go:72 /home/runner/work/gateway-operator/gateway-operator/test/envtest/kongconsumercredential_apikey_test.go:79]
    kongconsumercredential_apikey_test.go:119: FAIL: 1 out of 2 expectation(s) were met.
        	The code you are testing needs to make 1 more call(s).
        	at: [/home/runner/work/gateway-operator/gateway-operator/test/envtest/kongconsumercredential_apikey_test.go:119 /home/runner/go/pkg/mod/golang.org/[email protected]/src/runtime/asm_amd64.s:1695]
    controller.go:80: Test TestKongConsumerCredential_APIKey failed: dumping controller logs

This error means that we didn't wait for the credential to get programmed but got straight away to asserting on the mock expectations.

This PR changes that so that we first wait for the credential to get created and programmed (with Konnect ID).