CI: Restore tests for ebola, lassa, mumps, rsv

As per @victorlin 's recommendation in related change in conda-base,¹
these pathogens can get updated as post-merge tasks for eventual PRs.

¹ <nextstrain/conda-base#85 (comment)>

.github/workflows/ci.yml

@@ -215,7 +215,11 @@ jobs:
       matrix:
         include:
           - { pathogen: avian-flu,       build-args: test_target }
+          - { pathogen: ebola }
+          - { pathogen: lassa }
+          - { pathogen: mumps }
           - { pathogen: ncov,            build-args: all_regions -j 2 --profile nextstrain_profiles/nextstrain-ci }
+          - { pathogen: rsv }
           - { pathogen: seasonal-flu,    build-args: --configfile profiles/ci/builds.yaml -p }
 
     name: test-pathogen-repo-ci-v0 (${{ matrix.pathogen }})
@@ -247,7 +251,6 @@ jobs:
       # XXX TODO: Test on multiple platforms via the matrix too, as above?
       matrix:
         pathogen:
-          # XXX TODO: Restore pathogens after they've been updated (ebola, lassa, mumps, rsv)
           - dengue
           - measles
           - mpox