Fix offline test log matcher to use ContainSubstring

The offline test was using ContainLines() to check for 'Generating autoload files'
in the logs, which fails on Cloud Foundry because the logs channel may be consumed
or closed after deployment completes, making line-by-line matching unreliable.

Changed to use ContainSubstring() wrapped in SatisfyAll(), matching the pattern
used by all other working tests (composer_test.go, modules_test.go, etc.).

This fixes the test failure that occurred only on Cloud Foundry platform where
the test would timeout after 30 seconds even though the message was present in
the staging logs.

Author: ramonskie

src/php/integration/offline_test.go

@@ -43,9 +43,9 @@ func testOffline(platform switchblade.Platform, fixtures string) func(*testing.T
 					Execute(name, filepath.Join(fixtures, "vendored"))
 				Expect(err).NotTo(HaveOccurred())
 
-				Eventually(logs).Should(
-					ContainLines("Generating autoload files"),
-				)
+				Eventually(logs).Should(SatisfyAll(
+					ContainSubstring("Generating autoload files"),
+				))
 
 				Eventually(deployment).Should(Serve(
 					ContainSubstring("<p>App with dependencies running</p>"),