Revert "cleanup: Simplify usage of MinIOSourceProxyRequest (#19553)"

This reverts commit 928c0181bf.

This change was not correct, reverting.

We track 3 states with the ProxyRequest header - if replication process wants
to know if object is already replicated with a HEAD, it shouldn't proxy back
   - Poorna

cmd/object-api-options.go

@@ -66,8 +66,13 @@ func getDefaultOpts(header http.Header, copySource bool, metadata map[string]str
 	if crypto.S3.IsRequested(header) || (metadata != nil && crypto.S3.IsEncrypted(metadata)) {
 		opts.ServerSideEncryption = encrypt.NewSSE()
 	}
-	_, opts.ProxyRequest = header[xhttp.MinIOSourceProxyRequest]
-	_, opts.ReplicationRequest = header[xhttp.MinIOSourceReplicationRequest]
+	if v, ok := header[xhttp.MinIOSourceProxyRequest]; ok {
+		opts.ProxyHeaderSet = true
+		opts.ProxyRequest = strings.Join(v, "") == "true"
+	}
+	if _, ok := header[xhttp.MinIOSourceReplicationRequest]; ok {
+		opts.ReplicationRequest = true
+	}
 	opts.Speedtest = header.Get(globalObjectPerfUserMetadata) != ""
 	return
 }