[wp] Simplifies test content + fixes MemVar assigned

src/plugins/wp/MemVar.ml

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

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

...s/wp_acsl/oracle/assigned_initialized_memtyped.res.oracle

...sts/wp_acsl/oracle/assigned_initialized_memvar.res.oracle

...ped.0.session/cache/052040e80d2b0a66ce3f375f87b6ff42.json

...ped.0.session/cache/0a455ba1935274c35611d5fdf0fc2f8f.json

...ped.0.session/cache/1f0cf3c12d6f9cc69fd1da4055c79d9b.json

...ped.0.session/cache/3663b5118c844863a6d247b05714c0ce.json

...ped.0.session/cache/46d8e3b4a96b7cde8b04fa3be200b8a8.json

...ped.0.session/cache/5638c5e45ea8450040bc5a67415363a5.json

...ped.0.session/cache/5651f36fea599e9ff5d67e9df8679972.json

...ped.0.session/cache/84ac30ceabf40ae460d3a6638be6ea4d.json

...ped.0.session/cache/945f495a93303995087d23241c179c2f.json

...ped.0.session/cache/95004af59474d658afa48c1fddcc4b38.json

...ped.0.session/cache/afc7b014ce6a006d5c920be6c963bab6.json

...ped.0.session/cache/b8ca0e444c91c4ef4790a8775a3da864.json

...ped.0.session/cache/b9b74fb903d3948de1f1284737fcc1b4.json

...ped.0.session/cache/bdce48a1a69da57c8397d85bcbd98c2c.json

...ped.0.session/cache/c10d834a86946a7d1b5074a8355dfd03.json