rebase: bump google.golang.org/grpc from 1.67.1 to 1.68.0

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.67.1 to 1.68.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.67.1...v1.68.0)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Signed-off-by: Praveen M <m.praveen@ibm.com>

vendor/google.golang.org/grpc/internal/idle/idle.go

@@ -182,6 +182,7 @@ func (m *Manager) tryEnterIdleMode() bool {
 	return true
 }
 
+// EnterIdleModeForTesting instructs the channel to enter idle mode.
 func (m *Manager) EnterIdleModeForTesting() {
 	m.tryEnterIdleMode()
 }
@@ -225,7 +226,7 @@ func (m *Manager) ExitIdleMode() error {
 		//   came in and OnCallBegin() noticed that the calls count is negative.
 		// - Channel is in idle mode, and multiple new RPCs come in at the same
 		//   time, all of them notice a negative calls count in OnCallBegin and get
-		//   here. The first one to get the lock would got the channel to exit idle.
+		//   here. The first one to get the lock would get the channel to exit idle.
 		// - Channel is not in idle mode, and the user calls Connect which calls
 		//   m.ExitIdleMode.
 		//
@@ -266,6 +267,7 @@ func (m *Manager) isClosed() bool {
 	return atomic.LoadInt32(&m.closed) == 1
 }
 
+// Close stops the timer associated with the Manager, if it exists.
 func (m *Manager) Close() {
 	atomic.StoreInt32(&m.closed, 1)