We always run test steps on azure, even if a previous step failed, because we
don't want a failure in one configuration to prevent testing of other
configurations. However, if building PHP fails in the first place, then we
currently end up testing the system PHP binary. This is not only useless, but
will also result in a test runner hang and cause the job to time out.
Avoid this by using sapi/cli/php instead of the installed php as the test
binary. If we fail to build, then it will not exist, and testing will fail
immediately.
This uses a separate job template, because msan requires all used
libraries (apart from glibc) to be instrumented, so we can't link
any external libraries unless we recompile them. As such, we need
a much more minimal configure.
