test: tune the retryCap to stabalize the unit test (#920)

A 20ms retry cap seems not long enough for the test directories to be
created, e.g.: https://oss.gprow.dev/view/gs/oss-prow-build-kpt-config-sync/pr-logs/pull/GoogleContainerTools_kpt-config-sync/918/kpt-config-sync-presubmit/1709704761911021568

1. started calling readHydratedDirWithRetry at 2023-10-04 23:02:16.385300841
2. retryied 6 times whithin 20ms

   ```
   I1004 23:02:16.385422   17534 retry.go:75] failed to load the hydrated configs under /tmp/read-hydrated-dir-test3711104822/hydrated
   I1004 23:02:16.386681   17534 retry.go:75] failed to load the hydrated configs under /tmp/read-hydrated-dir-test3711104822/hydrated
   I1004 23:02:16.389097   17534 retry.go:75] failed to load the hydrated configs under /tmp/read-hydrated-dir-test3711104822/hydrated
   I1004 23:02:16.394563   17534 retry.go:75] failed to load the hydrated configs under /tmp/read-hydrated-dir-test3711104822/hydrated
   I1004 23:02:16.403944   17534 retry.go:75] failed to load the hydrated configs under /tmp/read-hydrated-dir-test3711104822/hydrated
   ```

3. sync directory created 68ms later: sync directory "/tmp/read-hydrated-dir-test3711104822/hydrated/1234567890abcde/configs" created at 2023-10-04 23:02:16.453810924
4. symlink created 69ms later: symlink "/tmp/read-hydrated-dir-test3711104822/hydrated/rev" created and linked to "/tmp/read-hydrated-dir-test3711104822/hydrated/1234567890abcde" at 2023-10-04 23:02:16.454404483

This commit increases the cap from 20ms to 100ms.

pkg/hydrate/controller_test.go

@@ -59,7 +59,7 @@ func TestSourceCommitAndDirWithRetry(t *testing.T) {
 		},
 		{
 			name:                 "source root directory created within the retry cap",
-			retryCap:             20 * time.Millisecond,
+			retryCap:             100 * time.Millisecond,
 			srcRootCreateLatency: 5 * time.Millisecond,
 			expectedSourceCommit: commit,
 		},
@@ -71,26 +71,26 @@ func TestSourceCommitAndDirWithRetry(t *testing.T) {
 		},
 		{
 			name:                 "symlink created within the retry cap",
-			retryCap:             20 * time.Millisecond,
+			retryCap:             100 * time.Millisecond,
 			symlinkCreateLatency: 5 * time.Millisecond,
 			expectedSourceCommit: commit,
 		},
 		{
 			name:           "error file exists with empty content",
-			retryCap:       10 * time.Millisecond,
+			retryCap:       100 * time.Millisecond,
 			errFileExists:  true,
 			expectedErrMsg: "is empty. Please check git-sync logs for more info",
 		},
 		{
 			name:           "error file exists with non-empty content",
-			retryCap:       10 * time.Millisecond,
+			retryCap:       100 * time.Millisecond,
 			errFileExists:  true,
 			errFileContent: "git-sync error",
 			expectedErrMsg: "git-sync error",
 		},
 		{
 			name:           "sync directory doesn't exist",
-			retryCap:       10 * time.Millisecond,
+			retryCap:       100 * time.Millisecond,
 			syncDir:        "unknown",
 			expectedErrMsg: "failed to evaluate the config directory",
 		},

pkg/parse/run_test.go

@@ -192,7 +192,7 @@ func TestRun(t *testing.T) {
 		{
 			id:                   "1",
 			name:                 "source commit directory created within the retry cap",
-			retryCap:             20 * time.Millisecond,
+			retryCap:             100 * time.Millisecond,
 			srcRootCreateLatency: 5 * time.Millisecond,
 			needRetry:            false,
 			expectedMsg:          "Sync Completed",

pkg/parse/source_test.go

@@ -164,20 +164,20 @@ func TestReadHydratedDirWithRetry(t *testing.T) {
 		{
 			name:                 "symlink created within the retry cap",
 			commit:               originCommit,
-			retryCap:             20 * time.Millisecond,
+			retryCap:             100 * time.Millisecond,
 			symlinkCreateLatency: 5 * time.Millisecond,
 			expectedCommit:       originCommit,
 		},
 		{
 			name:            "error file exists",
-			retryCap:        10 * time.Millisecond,
+			retryCap:        100 * time.Millisecond,
 			hydrationErr:    `{"code": "1068", "error": "actionable-error"}`,
 			expectedErrMsg:  "actionable-error",
 			expectedErrCode: status.ActionableHydrationErrorCode,
 		},
 		{
 			name:            "sync directory doesn't exist",
-			retryCap:        10 * time.Millisecond,
+			retryCap:        100 * time.Millisecond,
 			commit:          originCommit,
 			syncDir:         "unknown",
 			expectedErrMsg:  "failed to evaluate symbolic link to the hydrated sync directory",