[lldb] Increase timeout on lldbutil.wait_for_file_on_target (#189471)

I've been tracking sporadic timeouts waiting for a file to appear on
macOS buildbots (and occasionally local development environments). I
believe I've tracked it down to a regression in process launch
performance in macOS.

What I noticed is that running multiple test suites simultaneously
almost always triggered these failures and that the tests were always
waiting on files created by the inferior. Increasing this timeout no
longer triggers the failures on my loaded machine locally.

This timeout moves from about 16 seconds of total wait time to about 127
seconds of total wait time. This may feel a bit extreme, but this is a
performance issue. While I was here, I cleaned up logging code I was
using to investigate the test failures.

rdar://172122213

lldb/packages/Python/lldbsuite/test/lldbutil.py

@@ -1685,23 +1685,18 @@ def read_file_from_process_wd(test, name):
     return read_file_on_target(test, path)
 
 
-def wait_for_file_on_target(testcase, file_path, max_attempts=6):
-    for i in range(max_attempts):
+def wait_for_file_on_target(testcase, file_path):
+    import time
+
+    MAX_ATTEMPTS = 60
+    timeout_seconds = 20 if "ASAN_OPTIONS" in os.environ else 2
+    for i in range(MAX_ATTEMPTS):
         command = f"ls {file_path}"
         err, retcode, msg = testcase.run_platform_command(command)
-        if testcase.TraceOn():
-            testcase.trace(f"Ran command: {command}")
-            testcase.trace(f"Retcode: {retcode}")
-            testcase.trace(f"Output: {msg}")
-            testcase.trace(f"Error: {err.description}")
-
         if err.Success() and retcode == 0:
             break
-        if i < max_attempts:
-            # Exponential backoff!
-            import time
 
-            time.sleep(pow(2, i) * 0.25)
+        time.sleep(timeout_seconds)
     else:
         testcase.fail(
             "File %s not found even after %d attempts." % (file_path, max_attempts)