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/internal.go

@@ -191,6 +191,8 @@ var (
 	// ExitIdleModeForTesting gets the ClientConn to exit IDLE mode.
 	ExitIdleModeForTesting any // func(*grpc.ClientConn) error
 
+	// ChannelzTurnOffForTesting disables the Channelz service for testing
+	// purposes.
 	ChannelzTurnOffForTesting func()
 
 	// TriggerXDSResourceNotFoundForTesting causes the provided xDS Client to
@@ -205,10 +207,6 @@ var (
 	// default resolver scheme.
 	UserSetDefaultScheme = false
 
-	// ShuffleAddressListForTesting pseudo-randomizes the order of addresses.  n
-	// is the number of elements.  swap swaps the elements with indexes i and j.
-	ShuffleAddressListForTesting any // func(n int, swap func(i, j int))
-
 	// ConnectedAddress returns the connected address for a SubConnState. The
 	// address is only valid if the state is READY.
 	ConnectedAddress any // func (scs SubConnState) resolver.Address
@@ -235,7 +233,7 @@ var (
 //
 // The implementation is expected to create a health checking RPC stream by
 // calling newStream(), watch for the health status of serviceName, and report
-// it's health back by calling setConnectivityState().
+// its health back by calling setConnectivityState().
 //
 // The health checking protocol is defined at:
 // https://github.com/grpc/grpc/blob/master/doc/health-checking.md