fix(tsi1/partition/test): fix data races in test code (#57) (#25338)

* fix(tsi1/partition/test): fix data races in test code (#57)

* fix(tsi1/partition/test): fix data races in test code

This PR is like #24613 but solves it with a setter
method for MaxLogFileSize which allows unexporting that value and
MaxLogFileAge. There are actually two places locks were needed in test
code. The behavior of production code is unchanged.

(cherry picked from commit f0235c4daf4b97769db932f7346c1d3aecf57f8f)

* feat: modify error handling to be more idiomatic

closes #24042

* fix: errors.Join() filters nil errors

closes #25341
---------

Co-authored-by: Phil Bracikowski <[email protected]>
(cherry picked from commit 5c9e45f)

tsdb/index/tsi1/partition.go

@@ -116,8 +116,7 @@ func NewPartition(sfile *tsdb.SeriesFile, path string) *Partition {
 // Only for tests!
 func (p *Partition) SetMaxLogFileSize(new int64) (old int64) {
 	p.mu.Lock()
-	old = p.maxLogFileSize
-	p.maxLogFileSize = new
+	old, p.maxLogFileSize = p.maxLogFileSize, new
 	p.mu.Unlock()
 	return old
 }
@@ -357,7 +356,7 @@ func (p *Partition) CurrentCompactionN() int {
 }
 
 // Wait will block until all compactions are finished.
-// must only be called while they are disabled.
+// Must only be called while they are disabled.
 func (p *Partition) Wait() {
 	ticker := time.NewTicker(10 * time.Millisecond)
 	defer ticker.Stop()
@@ -387,15 +386,14 @@ func (p *Partition) Close() error {
 	}
 
 	// Close log files.
-	var err error
+	var err []error
 	for _, f := range p.fileSet.files {
-		if localErr := f.Close(); localErr != nil {
-			err = localErr
-		}
+		localErr := f.Close()
+		err = append(err, localErr)
 	}
 	p.fileSet.files = nil
 
-	return err
+	return errors.Join(err...)
 }
 
 // closing returns true if the partition is currently closing. It does not require