pw_rpc: Remove deprecated ServerContext& argument

The ServerContext& argument has been deprecated for a while. Remove it
to simplify the pw_rpc interface and reduce code size.

Requires: pigweed:70300
Requires: pigweed:70320
Requires: pigweed-internal:18220
Change-Id: If43f2073ef476dc5aa63be08f6893e3255d6aebe
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/69920
Reviewed-by: Alexei Frolov <frolv@google.com>
diff --git a/pw_file/flat_file_system.cc b/pw_file/flat_file_system.cc
index c7d2133..0cafd6b 100644
--- a/pw_file/flat_file_system.cc
+++ b/pw_file/flat_file_system.cc
@@ -75,8 +75,7 @@
   writer.Finish(OkStatus());
 }
 
-void FlatFileSystemService::List(ServerContext&,
-                                 ConstByteSpan request,
+void FlatFileSystemService::List(ConstByteSpan request,
                                  RawServerWriter& writer) {
   protobuf::Decoder decoder(request);
   // If a file name was provided, try and find and enumerate the file.
@@ -115,9 +114,7 @@
   EnumerateAllFiles(writer);
 }
 
-StatusWithSize FlatFileSystemService::Delete(ServerContext&,
-                                             ConstByteSpan request,
-                                             ByteSpan) {
+StatusWithSize FlatFileSystemService::Delete(ConstByteSpan request, ByteSpan) {
   protobuf::Decoder decoder(request);
   while (decoder.Next().ok()) {
     if (decoder.FieldNumber() !=