Update packaging for RL8

Description

This updates the packaging of LALInference, LALPulsar, and LALApps to support building on RL8:

1. LALInference is updated to not build against the MPI libraries, the way MPI codes need to be packaged changed in RHEL8 and is documented here, so we simply get around this by removing MPI from the RPMs. If the MPI codes are required they are available from Conda.
2. LALPulsar was updated to not include the hardware injection codes as this requires cds-crtools which is not available for RL8 via RPM and the CDS team have no plans to provide support for RPMs. These codes are included with the Conda packages for LALPulsar.
3. A bug was fixed in the LALApps dependencies which had it depending on python2.

API Changes and Justification

Backwards Compatible Changes

• This change does not modify any class/function/struct/type definitions in a public C header file or any Python class/function definitions
• This change adds new classes/functions/structs/types to a public C header file or Python module

Backwards Incompatible Changes

• This change modifies an existing class/function/struct/type definition in a public C header file or Python module
• This change removes an existing class/function/struct/type from a public C header file or Python module

If any of the Backwards Incompatible check boxes are ticked please provide a justification why this change is necessary and why it needs to be done in a backwards incompatible way.

Review Status

Please provide details on any reviews related to this change and and the associated reviewers.

lalapps/lalapps.spec.in

@@ -53,7 +53,7 @@ Requires: lalsimulation >= @MIN_LALSIMULATION_VERSION@
 Requires: less
 Requires: libframel >= @MIN_FRAMEL_VERSION@
 Requires: libmetaio >= @MIN_METAIO_VERSION@
-Requires: python
+Requires: python%{python3_pkgversion}
 Requires: python%{python3_pkgversion}-h5py
 Requires: python%{python3_pkgversion}-lal >= @MIN_LAL_VERSION@
 Requires: python%{python3_pkgversion}-lalframe >= @MIN_LALFRAME_VERSION@