Replace ErrorContains checks with Error checks before running upgrade downgrade

[GuptaManan100]

Description

This PR replaces the ErrorContains checks to just check for an Error instead while running upgrade downgrade tests. This is required because we don't guarantee that errors will be the same across different vitess version.

The workings of the changes can be seen in the workflow run https://github.com/vitessio/vitess/actions/runs/10630690740/job/29470087067?pr=16688 in the Convert ErrorContains to Error checks step. I am copying a snippet so that it can be seen directly here -

diff --git a/go/test/endtoend/backup/vtbackup/backup_only_test.go b/go/test/endtoend/backup/vtbackup/backup_only_test.go
index 7dada7a77d..1fd6c601cf 100644
--- a/go/test/endtoend/backup/vtbackup/backup_only_test.go
+++ b/go/test/endtoend/backup/vtbackup/backup_only_test.go
@@ -74,9 +74,9 @@ func TestTabletInitialBackup(t *testing.T) {
 	// For all version at or above v17.0.0, each replica will start in super_read_only mode. Let's verify that is working correctly.
 	if vtTabletVersion >= 17 {
 		err := primary.VttabletProcess.CreateDB("testDB")
-		require.ErrorContains(t, err, "The MySQL server is running with the --super-read-only option so it cannot execute this statement")
+		require.Error(t, err, "The MySQL server is running with the --super-read-only option so it cannot execute this statement")
 		err = replica1.VttabletProcess.CreateDB("testDB")
-		require.ErrorContains(t, err, "The MySQL server is running with the --super-read-only option so it cannot execute this statement")
+		require.Error(t, err, "The MySQL server is running with the --super-read-only option so it cannot execute this statement")
 	}
 
 	// Restore the Tablet
diff --git a/go/test/endtoend/mysqlctld/mysqlctld_test.go b/go/test/endtoend/mysqlctld/mysqlctld_test.go
index 328bc56337..9877219b50 100644
--- a/go/test/endtoend/mysqlctld/mysqlctld_test.go
+++ b/go/test/endtoend/mysqlctld/mysqlctld_test.go
@@ -175,5 +175,5 @@ func TestReadBinlogFilesTimestamps(t *testing.T) {
 	client, err := mysqlctlclient.New(context.Background(), "unix", primaryTablet.MysqlctldProcess.SocketFile)
 	require.NoError(t, err)
 	_, err = client.ReadBinlogFilesTimestamps(context.Background(), &mysqlctl.ReadBinlogFilesTimestampsRequest{})
-	require.ErrorContains(t, err, "empty binlog list in ReadBinlogFilesTimestampsRequest")
+	require.Error(t, err, "empty binlog list in ReadBinlogFilesTimestampsRequest")
 }

This change is required so that we can get this CI check to work https://github.com/vitessio/vitess/actions/runs/10488116666/job/29052695413?pr=16619. This works in conjunction with #16672 that fixes some anti-patterns in the test.

Related Issue(s)

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

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[vitess-bot]

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[harshit-gangal]

There could be a possible use of EqualError as well.
Let's discourage that for end to end test.

[GuptaManan100]

Good point, I updated the PR to also change EqualError to Error

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.93%. Comparing base (977b9a3) to head (caaa699).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16688      +/-   ##
==========================================
- Coverage   68.95%   68.93%   -0.02%     
==========================================
  Files        1565     1565              
  Lines      201530   201556      +26     
==========================================
- Hits       138957   138943      -14     
- Misses      62573    62613      +40     

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