[Flaky test] Coverage test failing intermittently due to panic

Description: Coverage test failing due to panic in goroutine after TestConfigLoaderStandaloneExtensionServerAndCustomResource has completed. Retry succeeds.

Repro steps: https://github.com/envoyproxy/gateway/actions/runs/24496848059/job/71593709753

Environment: CI

Logs:

1.7763234386184103e+09	info	config-loader	loader/configloader.go:119	running hook
panic: Log in goroutine after TestConfigLoaderStandaloneExtensionServerAndCustomResource has completed: config changed 3 times
	

goroutine 25 [running]:
testing.(*common).log(0xc00030a248, {0xc0000461b0, 0x16})
	/opt/hostedtoolcache/go/1.26.2/x64/src/testing/testing.go:1039 +0x1df
testing.(*common).Logf(0xc00030a248, {0x1a0730f, 0x17}, {0xc000318e88, 0x1, 0x1})
	/opt/hostedtoolcache/go/1.26.2/x64/src/testing/testing.go:1200 +0x8f
github.com/envoyproxy/gateway/internal/envoygateway/config/loader.TestConfigLoaderStandaloneExtensionServerAndCustomResource.func3({0x1aa72d8?, 0xc00017c190?}, 0xc0001a4090)
	/home/runner/work/gateway/gateway/internal/envoygateway/config/loader/configloader_test.go:93 +0xc5
github.com/envoyproxy/gateway/internal/envoygateway/config/loader.(*Loader).runHook.func1({0x1aa72d8, 0xc00017c190})
	/home/runner/work/gateway/gateway/internal/envoygateway/config/loader/configloader.go:129 +0x13e
created by github.com/envoyproxy/gateway/internal/envoygateway/config/loader.(*Loader).runHook in goroutine 44
	/home/runner/work/gateway/gateway/internal/envoygateway/config/loader/configloader.go:124 +0x325
FAIL	github.com/envoyproxy/gateway/internal/envoygateway/config/loader	0.110s