[CI] Remove duplicate make invocations

@dimakuv:
> This is an artifact from the old Jenkins, maybe we should fix this
> now. Here, we ask to build and prepare all tests (make .. test and
> make .. sgx-tokens). But below, in each test directory, we perform the
> same actions again. That's why I even had to add a bogus make clean &&
> make all to the LibOS/shim/test/regression case.
>
> Let's finally remove this duplication. Basically, we'll need to move
> RA_CLIENT_SPID in this target and only keep make regression/make test
> in the other targets.

.ci/lib/stage-test.jenkinsfile

@@ -1,9 +1,7 @@
 stage('test') {
     sh '''
-        make ${MAKEOPTS} test
         if test -n "$SGX"
         then
-            make ${MAKEOPTS} sgx-tokens
             make ${MAKEOPTS} -C Pal/src/host/Linux-SGX/tools install \
                 PREFIX=../../../../../../LibOS/shim/test/fs
         fi
@@ -29,7 +27,6 @@ stage('test') {
         try {
             sh '''
                 cd LibOS/shim/test/regression
-                make clean  # re-build with ra_client_spid set
                 make ${MAKEOPTS} RA_CLIENT_SPID=${ra_client_spid} all
                 if test -n "$SGX"
                 then