Trac #29665: fix sage.misc.package doctest with system alabaster.

When alabaster from the system is used, these tests won't be able to
find its SPKG installed. Add some ellipses, and switch one test to
look for sage_conf instead.

Author: orlitzky

src/sage/misc/package.py

@@ -389,9 +389,9 @@ def installed_packages(exclude_pip=True):
     EXAMPLES::
 
         sage: sorted(installed_packages().keys())  # optional - sage_spkg
-        [...'gmpy2', ...'sage_conf', ...]
-        sage: installed_packages()['gmpy2']  # optional - sage_spkg, random
-        '2.1.0b5'
+        [...'sage_conf', ...]
+        sage: installed_packages()['sage_conf']  # optional - sage_spkg, random
+        '9.5'
 
     .. SEEALSO::