use default HTTP/2 handshake strategy for grpc

doc/release_notes/1_0_0.md

@@ -42,3 +42,8 @@
 
 * `:datadog` adapter only supports `ddtrace` gem 1.x or higher.
 * `:faraday` adapter only supports `faraday` gem 1.x or higher.
+
+### chore
+
+* `:grpc` plugin: connection won't buffer requests before HTTP/2 handshake is commpleted, i.e. works the same as plain `httpx` HTTP/2 connection establishment.
+  * if you are relying on this, you can keep the old behavior this way: `HTTPX.plugin(:grpc, http2_settings: { wait_for_handshake: false })`.

lib/httpx/plugins/grpc.rb

@@ -62,7 +62,6 @@ module HTTPX
         def extra_options(options)
           options.merge(
             fallback_protocol: "h2",
-            http2_settings: { wait_for_handshake: false },
             grpc_rpcs: {}.freeze,
             grpc_compression: false,
             grpc_deadline: DEADLINE