Remove stray comment reference to "no_" prefix for boolean flags which was removed in https://github.com/bazelbuild/bazel/commit/ca600bf2d014650b1f1ecb5214878b09a0838086.

RELNOTES: None
PiperOrigin-RevId: 167202392

src/main/protobuf/invocation_policy.proto

diff --git a/src/main/protobuf/invocation_policy.proto b/src/main/protobuf/invocation_policy.proto
index f14db3e..92a0da3 100644
--- a/src/main/protobuf/invocation_policy.proto
+++ b/src/main/protobuf/invocation_policy.proto
@@ -35,7 +35,7 @@
   // name of the flag. If the user specifies the abbreviated name of a flag,
   // that flag will be matched using its full name.
   //
-  // The "no" and "no_" prefixes will not be parsed, so for boolean flags, use
+  // The "no" prefix will not be parsed, so for boolean flags, use
   // the flag's full name and explicitly set it to true or false.
   optional string flag_name = 1;