MDBF-883 - CentOS 7 bintar compatibility with old buildbot

As part of the MDBF, I am preparing several (manual) changes
to the centos-7-bintar container image, one of which will bump
GnuTLS version to 3.7.x, as in buildbot.mariadb.net

GNUTLS_NO_SIGNAL flag was introduced in GnuTLS 3.4.x so there's no
need to disable the macro anymore. (the flag is not present in buildbot.mariadb.net)

More on that, from my tests (10.11), disabling the macro will cause the compilation to fail
when using the newer GnuTLS (static library).
<command-line>:0:18: error: expected identifier before numeric constant.

Important notes:
This code change should only be deployed in Production when the updated centos7-bintar is published in quay, in this order:
  - deploy code changes
  - stop master-docker-nonstandard (where the builder is defined)
  - update image on quay
  - start master-docker-nonstandard

  I will probably deploy this change manually because there are some pending
  other changes which need to be tested and given the BLOCKER
  status of the MDBF, it should be deployed ASAP.

master-docker-nonstandard/master.cfg

@@ -1347,15 +1347,14 @@ f_bintar.addStep(
             "sh",
             "-c",
             util.Interpolate(
-                'cmake . -DWITH_READLINE=1 -DCURSES_NEED_NCURSES=1 -DBUILD_CONFIG=mysql_release -DCMAKE_C_FLAGS="%(kw:gnutls_no_signal)s" -DCMAKE_CXX_FLAGS="%(kw:gnutls_no_signal)s" -DWITH_SSL=bundled -DPLATFORM=linux-systemd && make -j%(kw:jobs)s package',
+                'cmake . -DWITH_READLINE=1 -DCURSES_NEED_NCURSES=1 -DBUILD_CONFIG=mysql_release -DWITH_SSL=bundled -DPLATFORM=linux-systemd && make -j%(kw:jobs)s package',
                 perf_schema=util.Property("perf_schema", default="YES"),
                 build_type=util.Property("build_type", default="RelWithDebInfo"),
                 jobs=util.Property("jobs", default="$(getconf _NPROCESSORS_ONLN)"),
                 c_compiler=util.Property("c_compiler", default="gcc"),
                 cxx_compiler=util.Property("cxx_compiler", default="g++"),
                 additional_args=util.Property("additional_args", default=""),
                 create_package=util.Property("create_package", default="package"),
-                gnutls_no_signal=util.Property("gnutls_no_signal", default=" "),
             ),
         ],
         env={
@@ -1703,7 +1702,6 @@ c["builders"].append(
         nextBuild=nextBuild,
         canStartBuild=canStartBuild,
         locks=getLocks,
-        properties={"gnutls_no_signal": "-DGNUTLS_NO_SIGNAL=0"},
         factory=f_bintar,
     )
 )