…ry to grpc_ssl_credentials." (grpc#34355)

This reverts commit a4ac80c.

…c_ssl_credentials, version 2. (#34408)

Revert the reversion of the SSL_CTX_new change (#34355 reverted #34180 )
with a fix.

There was an issue with using `strcpy` on a `new[] string` in the
constructor of `ssl_credentials`. An ASAN test caught this in some CI
down the line - `ERROR: AddressSanitizer: alloc-dealloc-mismatch
(operator new [] vs free)`

That `strcpy` call was changed to `grp_strdup` which duplicates a string
in a way that can be freed by `gpr_free` and should resolve the ASAN
failure.