Revert "Set the "build_jobs" on concretization/generate for CI (#47660)" (#48028)

This reverts commit 316dcc1609.

lib/spack/spack/cmd/ci.py

@@ -17,7 +17,6 @@
 import spack.ci as spack_ci
 import spack.cmd
 import spack.cmd.buildcache as buildcache
-import spack.cmd.common.arguments
 import spack.config as cfg
 import spack.environment as ev
 import spack.hash_types as ht
@@ -117,9 +116,6 @@ def setup_parser(subparser):
     )
     generate.set_defaults(func=ci_generate)
 
-    spack.cmd.common.arguments.add_concretizer_args(generate)
-    spack.cmd.common.arguments.add_common_arguments(generate, ["jobs"])
-
     # Rebuild the buildcache index associated with the mirror in the
     # active, gitlab-enabled environment.
     index = subparsers.add_parser(
@@ -149,7 +145,6 @@ def setup_parser(subparser):
         help="stop stand-alone tests after the first failure",
     )
     rebuild.set_defaults(func=ci_rebuild)
-    spack.cmd.common.arguments.add_common_arguments(rebuild, ["jobs"])
 
     # Facilitate reproduction of a failed CI build job
     reproduce = subparsers.add_parser(
@@ -445,9 +440,6 @@ def ci_rebuild(args):
     if not verify_binaries:
         install_args.append("--no-check-signature")
 
-    if args.jobs:
-        install_args.append("-j{args.jobs}")
-
     slash_hash = spack_ci.win_quote("/" + job_spec.dag_hash())
 
     # Arguments when installing the root from sources