Update fre-cli container build

[singhd789]

Describe the bug

1. Dockerfile/build currently uses a conda-forge base image but we want to move to a simpler ubuntu base
2. cylc-flow-tools environment yaml needs an updated hsm (1.4.0) AND for fre-nctools to be included again (previously in fre-cli environment but was removed for conflicts)
3. Dockerfile can add conda environemtn to the path so it is automatically activated upon running the container - which would allow us to remove conda init .... activate from the runcript.sh