modify the test so that Sage's "table" is not used

see https://trac.sagemath.org/ticket/31498#comment:5
for reasoning

Also, removed useless lines in a not-tested test

src/sage/tests/gap_packages.py

@@ -5,11 +5,11 @@
 
     sage: from sage.tests.gap_packages import all_installed_packages, test_packages
     sage: pkgs = all_installed_packages(ignore_dot_gap=True)
-    sage: test_packages(pkgs, only_failures=True)    # optional - gap_packages
-    ...
-      Status   Package   GAP Output
-    +--------+---------+------------+
-
+    sage: libgap.SetInfoLevel(libgap.InfoWarning, 0)
+    sage: for p in pkgs:
+    ....:     pkg = p.split('-')[0]
+    ....:     if not libgap.LoadPackage(pkg):
+    ....:         raise
     sage: test_packages(['atlasrep', 'tomlib'])
       Status   Package    GAP Output
     +--------+----------+------------+
@@ -55,36 +55,6 @@ def test_packages(packages, only_failures=False):
         +---------+------------+------------+
                    Alnuth       true
                    GAPDoc       true
-                   HAPcryst     true
-                   Hap          true
-                   QPA          true
-                   aclib        true
-                   atlasrep     true
-                   autpgrp      true
-                   cohomolo     true
-                   corelg       true
-                   crime        true
-                   cryst        true
-                   crystcat     true
-                   ctbllib      true
-                   design       true
-                   factint      true
-                   gbnp         true
-                   grape        true
-                   guava        true
-                   happrime     true
-                   hecke        true
-                   laguna       true
-                   liealgdb     true
-                   liepring     true
-                   liering      true
-                   loops        true
-                   mapclass     true
-                   polycyclic   true
-                   polymaking   true
-                   quagroup     true
-                   repsn        true
-                   sla          true
                    sonata       true
                    tomlib       true
                    toric        true