[WP] avoid using -wp-gen -wp-prover why3:xxx in tests on non-qualif config

src/plugins/wp/tests/wp_acsl/boolean.i

 /* run.config
-OPT: -wp-prover alt-ergo -wp-gen
+DONTRUN: only usable in qualif config
 */
  /*@
         logic boolean u8_continue_f(unsigned char b) =
@@ -8,7 +8,7 @@ OPT: -wp-prover alt-ergo -wp-gen
 
     /*@
         assigns \nothing;
-        ensures  u8_continue_f(b) == \result==1;
+        ensures  u8_continue_f(b) == \result;
     */
     int u8_is_continue(const unsigned char b)
     {

src/plugins/wp/tests/wp_acsl/oracle_qualif/boolean.0.report.json

+{ "wp:global": { "why3:Alt-Ergo,2.0.0": { "total": 1, "valid": 1,
+                                          "rank": 10 },
+                 "qed": { "total": 3, "valid": 3 },
+                 "wp:main": { "total": 4, "valid": 4, "rank": 10 } },
+  "wp:functions": { "u8_is_continue": { "u8_is_continue_assigns": { "qed": 
+                                                                    { "total": 3,
+                                                                    "valid": 3 },
+                                                                    "wp:main": 
+                                                                    { "total": 3,
+                                                                    "valid": 3 } },
+                                        "u8_is_continue_ensures": { "why3:Alt-Ergo,2.0.0": 
+                                                                    { "total": 1,
+                                                                    "valid": 1,
+                                                                    "rank": 10 },
+                                                                    "wp:main": 
+                                                                    { "total": 1,
+                                                                    "valid": 1,
+                                                                    "rank": 10 } },
+                                        "wp:section": { "why3:Alt-Ergo,2.0.0": 
+                                                          { "total": 1,
+                                                            "valid": 1,
+                                                            "rank": 10 },
+                                                        "qed": { "total": 3,
+                                                                 "valid": 3 },
+                                                        "wp:main": { "total": 4,
+                                                                    "valid": 4,
+                                                                    "rank": 10 } } } } }

src/plugins/wp/tests/wp_acsl/oracle_qualif/boolean.res.oracle

+# frama-c -wp [...]
+[kernel] Parsing tests/wp_acsl/boolean.i (no preprocessing)
+[wp] Running WP plugin...
+[wp] Loading driver 'share/wp.driver'
+[wp] Warning: Missing RTE guards
+[wp] 4 goals scheduled
+[wp] [Alt-Ergo 2.0.0] Goal typed_u8_is_continue_ensures : Valid
+[wp] [Qed] Goal typed_u8_is_continue_assigns_part1 : Valid
+[wp] [Qed] Goal typed_u8_is_continue_assigns_part2 : Valid
+[wp] [Qed] Goal typed_u8_is_continue_assigns_part3 : Valid
+[wp] Proved goals:    4 / 4
+  Qed:               3 
+  Alt-Ergo 2.0.0:    1
+[wp] Report in:  'tests/wp_acsl/oracle_qualif/boolean.0.report.json'
+[wp] Report out: 'tests/wp_acsl/result_qualif/boolean.0.report.json'
+-------------------------------------------------------------
+Functions           WP     Alt-Ergo        Total   Success
+u8_is_continue       3      1 (36..48)       4       100%
+-------------------------------------------------------------