acc: Fix priority of stubs in test.toml (#2339)

## Changes
Reverse the order of stubs to match expectation (leaf configuration
takes precedence over parent configuration).
Follow up to #2334 .

## Tests
acceptance/selftest/server is extended with duplicate handler

acceptance/acceptance_test.go

@@ -259,6 +259,10 @@ func runTest(t *testing.T, dir, coverDir string, repls testdiff.ReplacementsCont
 			server.RecordRequests = config.RecordRequests
 			server.IncludeRequestHeaders = config.IncludeRequestHeaders
 
+			// We want later stubs takes precedence, because then leaf configs take precedence over parent directory configs
+			// In gorilla/mux earlier handlers take precedence, so we need to reverse the order
+			slices.Reverse(config.Server)
+
 			for _, stub := range config.Server {
 				require.NotEmpty(t, stub.Pattern)
 				items := strings.Split(stub.Pattern, " ")

acceptance/selftest/server/test.toml

@@ -1,6 +1,10 @@
 LocalOnly = true
 RecordRequests = true
 
+[[Server]]
+Pattern = "GET /custom/endpoint"
+Response.Body = '''should not see this response, latter response takes precedence'''
+
 [[Server]]
 Pattern = "GET /custom/endpoint"
 Response.Body = '''custom