amend kopia error clues (#2588)

## Does this PR need a docs update or release note?

- [x] ⛔ No 

## Type of change

- [x] 🧹 Tech Debt/Cleanup

## Issue(s)

* #1970

## Test Plan

- [x] ⚡ Unit test
- [x] 💚 E2E

src/internal/connector/exchange/api/contacts.go

@@ -101,8 +101,7 @@ func (c Contacts) GetContainerByID(
 
 // EnumerateContainers iterates through all of the users current
 // contacts folders, converting each to a graph.CacheFolder, and calling
-// fn(cf) on each one.  If fn(cf) errors, the error is aggregated
-// into a multierror that gets returned to the caller.
+// fn(cf) on each one.
 // Folder hierarchy is represented in its current state, and does
 // not contain historical data.
 func (c Contacts) EnumerateContainers(

src/internal/connector/exchange/api/events.go

@@ -133,8 +133,7 @@ func (c Events) GetItem(
 
 // EnumerateContainers iterates through all of the users current
 // calendars, converting each to a graph.CacheFolder, and
-// calling fn(cf) on each one.  If fn(cf) errors, the error is
-// aggregated into a multierror that gets returned to the caller.
+// calling fn(cf) on each one.
 // Folder hierarchy is represented in its current state, and does
 // not contain historical data.
 func (c Events) EnumerateContainers(

src/internal/connector/exchange/api/mail.go

@@ -156,8 +156,7 @@ func (c Mail) GetItem(
 
 // EnumerateContainers iterates through all of the users current
 // mail folders, converting each to a graph.CacheFolder, and calling
-// fn(cf) on each one.  If fn(cf) errors, the error is aggregated
-// into a multierror that gets returned to the caller.
+// fn(cf) on each one.
 // Folder hierarchy is represented in its current state, and does
 // not contain historical data.
 func (c Mail) EnumerateContainers(

src/internal/operations/backup.go

@@ -469,16 +469,15 @@ func consumeBackupDataCollections(
 			return nil, nil, nil, err
 		}
 
-		return nil, nil, nil, errors.Wrapf(
-			err,
-			"kopia snapshot failed with %v catastrophic errors and %v ignored errors",
-			kopiaStats.ErrorCount, kopiaStats.IgnoredErrorCount)
+		return nil, nil, nil, clues.Stack(err).With(
+			"kopia_errors", kopiaStats.ErrorCount,
+			"kopia_ignored_errors", kopiaStats.IgnoredErrorCount)
 	}
 
 	if kopiaStats.ErrorCount > 0 || kopiaStats.IgnoredErrorCount > 0 {
-		err = errors.Errorf(
-			"kopia snapshot failed with %v catastrophic errors and %v ignored errors",
-			kopiaStats.ErrorCount, kopiaStats.IgnoredErrorCount)
+		err = clues.New("building kopia snapshot").With(
+			"kopia_errors", kopiaStats.ErrorCount,
+			"kopia_ignored_errors", kopiaStats.IgnoredErrorCount)
 	}
 
 	return kopiaStats, deets, itemsSourcedFromBase, err