Timestamp string conversion is not deterministic

### Description

Critical areas of the code like https://github.com/hyperledger/fabric/blob/c24c9b57439cfb1a9c2332d953286946ebfc3600/orderer/common/cluster/util.go#L812-L820
are using timestamp's `String()` method in order to calculate it's string representation.

The string method uses:
https://github.com/hyperledger/fabric/blob/c24c9b57439cfb1a9c2332d953286946ebfc3600/vendor/google.golang.org/protobuf/types/known/timestamppb/timestamp.pb.go#L271-L273

https://github.com/hyperledger/fabric/blob/c24c9b57439cfb1a9c2332d953286946ebfc3600/vendor/google.golang.org/protobuf/internal/impl/api_export.go#L173-L177

https://github.com/hyperledger/fabric/blob/c24c9b57439cfb1a9c2332d953286946ebfc3600/vendor/google.golang.org/protobuf/encoding/prototext/encode.go#L85-L98

Which clearly states "**Do not depend on the output being stable. It may change over time across different versions of the program.**".

Evidence to that is the way the timestamp `seconds:1693225332; nanos:471402000` is converted to string:
- `seconds:1693225332 nanos:471402000`
- `seconds:1693225332 nanos:471402000`
note the double vs single spacing.

This string is then converted to bytes array and it's hash is used to calculated different security components.

### Steps to reproduce

_No response_