Removed all http_proxy reference from build.

Removed all http_proxy reference from build.
http_proxy is an environment configuration and should not be defined in
in the build script.
If you need to use a proxy to build docker images then add it to
the mvn command like this :

-Ddocker.buildArg.http_proxy=$PROXY -Ddocker.buildArg.https_proxy=$PROXY

Also adding http_proxy in the Dockerfile directly will add the
environment variable in the POD statically using the proxy the was
built with at runtime.

If a proxy is needed at runtime then the environment variables should be
injecting using helm charts and overrides.

Issue-ID: CCSDK-1877
Signed-off-by: Sebastien Premont-Tendland <sebastien.premont@bell.ca>
Change-Id: I2b99b277b594408c974cf29a5804384293776a22