[alias] be less verbose for unanalysed functions

src/plugins/alias/src/analysis.ml

src/plugins/alias/tests/basic/oracle/function2.res.oracle

src/plugins/alias/tests/basic/oracle/while_for1.res.oracle

src/plugins/alias/tests/offsets/oracle/array3.res.oracle

src/plugins/alias/tests/offsets/oracle/nested1.res.oracle

src/plugins/alias/tests/offsets/oracle/nested2.res.oracle

src/plugins/alias/tests/offsets/oracle/structure4.res.oracle

src/plugins/alias/tests/offsets/oracle/structure5.res.oracle

...plugins/alias/tests/real_world/oracle/example1.res.oracle

...plugins/alias/tests/real_world/oracle/example2.res.oracle

...ins/alias/tests/real_world/oracle/function1_v2.res.oracle