Enable redismodule UT in CI pipeline

Enable redismodule UT in CI pipeline

Add new build stage to 'Dockerfile.redis'
that runs unit tests with valgrind in ubuntu-based
container.

Also run unit tests without valgrind in the actual
build stage. Valgrind is not run at this stage
because alpine-linux uses musl implementation
of libc which causes valgrind to emit false
positives.

Unit tests and valgrind memory checks are now enabled
by default. They can be disabled with the configure options:
'--disable-unit-test' and '--disable-unit-test-memcheck'
respectively.

Disabled cpputest's builtin memory checks in UT even if
they are available.

Updated redismodule/README.md on compiling redismodule.

Removed some Nokia-specific scripts.

Signed-off-by: Arvo Heinonen <arvo.heinonen@nokia.com>
Change-Id: Id7c37f6a99888d1a9229ca41dd7cbc325b6d495f