Due to https://github.com/grpc/grpc/issues/31772 we need to move back to grpc-1.49.x

I attempted to use the SRPM and build from there, but I ran into some issues because it
required devtools-6, which I couldn't track down for centos7.  I changed the dependency
to devtools-7 and was able to build it, but we are now getting segfaults in phpunit
during shutdown. 

I have now been trying to build it from source, but running into issues where grpc requires
std=c++14, and centos7 gcc (4.8.5) is too old to support c++14.

I'm curious how y'all were able to build grpc-1.49.0 for centos7 at all.  At this point I'm
going to try upgrading gcc on my build box and go from there, but if there's a better path
I'd love to hear it.

Thanks,
Tim