Upgrade to grpc 1.30

[pracucci]

This is a draft PR to investigate if we're willing to upgrade to grpc 1.30 at this stage.

Fixes #12153.

[pracucci]

There's a failing unit test for which I would need some input to fix it:

panic: field raftpb.Message.type has invalid type: got raftpb.MessageType, want pointer

goroutine 64 [running]:
google.golang.org/protobuf/internal/impl.fieldInfoForScalar(0x1723700, 0xc0001b5500, 0x158cd55, 0x4, 0x0, 0x0, 0x1723820, 0x15ab480, 0x158cd5b, 0x45, ...)
	/workspace/pkg/mod/google.golang.org/[email protected]/internal/impl/message_reflect_field.go:228 +0x800
google.golang.org/protobuf/internal/impl.(*MessageInfo).makeKnownFieldsFunc(0xc000150a00, 0xffffffffffffffff, 0xffffffffffffffff, 0x150, 0xffffffffffffffff, 0xc0002bc480, 0xc0002bc4b0, 0xc0002bc4e0, 0xc0002bc510)
	/workspace/pkg/mod/google.golang.org/[email protected]/internal/impl/message_reflect.go:67 +0x938
google.golang.org/protobuf/internal/impl.(*MessageInfo).makeReflectFuncs(0xc000150a00, 0x1723820, 0x1614500, 0xffffffffffffffff, 0xffffffffffffffff, 0x150, 0xffffffffffffffff, 0xc0002bc480, 0xc0002bc4b0, 0xc0002bc4e0, ...)
	/workspace/pkg/mod/google.golang.org/[email protected]/internal/impl/message_reflect.go:36 +0x63
google.golang.org/protobuf/internal/impl.(*MessageInfo).initOnce(0xc000150a00)
	/workspace/pkg/mod/google.golang.org/[email protected]/internal/impl/message.go:90 +0x182
google.golang.org/protobuf/internal/impl.(*MessageInfo).init(0xc000150a00)
	/workspace/pkg/mod/google.golang.org/[email protected]/internal/impl/message.go:72 +0x3c
google.golang.org/protobuf/internal/impl.(*messageReflectWrapper).Has(0xc0000579d0, 0x1723700, 0xc0001b5500, 0xc0001b5500)
	/workspace/pkg/mod/google.golang.org/[email protected]/internal/impl/message_reflect_gen.go:185 +0x33
github.com/golang/protobuf/proto.(*textWriter).writeMessage(0xc0002bc1e0, 0x171fa00, 0xc0000579d0, 0x0, 0x0)
	/workspace/pkg/mod/github.com/golang/[email protected]/proto/text_encode.go:278 +0x925
github.com/golang/protobuf/proto.(*TextMarshaler).marshal(0x1aa749c, 0x1715380, 0xc0002ab080, 0x45, 0x0, 0x0, 0x1149948, 0x0)
	/workspace/pkg/mod/github.com/golang/[email protected]/proto/text_encode.go:86 +0x18a
github.com/golang/protobuf/proto.(*TextMarshaler).Text(...)
	/workspace/pkg/mod/github.com/golang/[email protected]/proto/text_encode.go:44
github.com/golang/protobuf/proto.CompactTextString(...)
	/workspace/pkg/mod/github.com/golang/[email protected]/proto/text_encode.go:106
go.etcd.io/etcd/v3/raft/raftpb.(*Message).String(...)
	/workspace/src/github.com/etcd-io/etcd/raft/raftpb/raft.pb.go:312
go.etcd.io/etcd/v3/raft.TestNodeProposeWaitDropped.func1(0xc000296c80, 0x2, 0x0, 0x1, 0x0, 0x0, 0x0, 0xc0002b05f0, 0x1, 0x1, ...)
	/workspace/src/github.com/etcd-io/etcd/raft/node_test.go:462 +0x312
go.etcd.io/etcd/v3/raft.(*raft).Step(0xc000296c80, 0x2, 0x0, 0x1, 0x0, 0x0, 0x0, 0xc0002b05f0, 0x1, 0x1, ...)
	/workspace/src/github.com/etcd-io/etcd/raft/raft.go:985 +0x11a2
go.etcd.io/etcd/v3/raft.(*node).run(0xc000021ce0)
	/workspace/src/github.com/etcd-io/etcd/raft/node.go:346 +0xcfa
created by go.etcd.io/etcd/v3/raft.TestNodeProposeWaitDropped
	/workspace/src/github.com/etcd-io/etcd/raft/node_test.go:474 +0x521
FAIL	go.etcd.io/etcd/v3/raft	0.033s

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed after 21 days if no further activity occurs. Thank you for your contributions.

[pracucci]

Closing because other (better) attempts are in progress.