Attempt to fix flaky TestGetRoundTripper* tests

[albertteoh]

Which problem is this PR solving?

• Resolves Flaky test TestGetRoundTripperTLSConfig #4732

Description of the changes

• Introduces an atomic boolean outside of the HTTP test handler and only set to true if the expected request is received.
• This should prevent cases where unrelated processes are hitting the same test URL.

How was this change tested?

• Ran make test to pass.
• Ran go test -tags=memory_storage_integration -count 10 ./... and confirmed metricsstore tests are passing.
• Note that a number of unrelated tests were failing with the -count 10 flag set, not as a result of the changes from this PR, namely:

--- FAIL: TestFactory (0.00s)
    --- FAIL: TestFactory/#00 (0.00s)
panic: Reuse of exported var name: test_1694287567920905000_counter_x
 [recovered]
	panic: Reuse of exported var name: test_1694287567920905000_counter_x

and

--- FAIL: TestPublishOpts (0.00s)
    builder_test.go:308:
        	Error Trace:	/Users/albertteoh/go/src/github.com/albertteoh/jaeger/cmd/agent/app/builder_test.go:308
        	Error:      	Received unexpected error:
        	            	cannot create processors: cannot create Thrift Processor: cannot create UDP Server: cannot create UDPServerTransport: listen udp :5775: bind: address already in use
        	Test:       	TestPublishOpts

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: yarn lint and yarn test

[codecov]

Codecov Report

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[yurishkuro]

Using boolean in the assert is not the best output when the assert fails. Using the actual string produces much more intuitive output in case of test failure.

[yurishkuro]

Suggested change

	var authReceived atomic.Bool
	var authReceived atomic.Pointer[string]

[yurishkuro]

Suggested change

	if r.Header.Get("Authorization") == "Bearer foo" {
	authReceived.Store(true)
	}
	h := r.Header.Get("Authorization")
	authReceived.Store(&h)

[yurishkuro]

Suggested change

	assert.True(t, authReceived.Load())
	assert.Equal(t, "Bearer foo", *authReceived.Load())

[yurishkuro]

Suggested change

	_, err = fmt.Fprintln(w, string(bytes))
	_, err = w.Write(bytes)

[albertteoh]

Using boolean in the assert is not the best output when the assert fails. Using the actual string produces much more intuitive output in case of test failure.

Good suggestion, addressed in: 31bdc02