Mark quick "THOROUGH" tests as "CORE"

These perhaps used to take much longer, but currently complete within a
small number of seconds (with both MiniSat and CaDiCaL as back-ends):

* ConstantEvaluationToString01/test_long_no_propagation2.desc:
  * cadical: 11 seconds
  * minisat: 9 seconds
* StringBuilderChars01/test.desc:
  * cadical: 8 seconds
  * minisat: 4 seconds
* StringIndexMethods01/test.desc:
  * cadical: 0 seconds
  * minisat: 0 seconds
* StringIndexOf/test_thorough.desc:
  * cadical: 1 seconds
  * minisat: 2 seconds
* StringStartEnd01/test.desc:
  * cadical: 0 seconds
  * minisat: 0 seconds
* StringStartEnd03/test.desc:
  * cadical: 0 seconds
  * minisat: 0 seconds
* location15/test.desc:
  * cadical: 5 seconds
  * minisat: 5 seconds

Author: tautschnig

jbmc/regression/jbmc-strings/ConstantEvaluationToString01/test_long_no_propagation2.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 Main
 --function Main.testLongToStringNoPropagation2 --cp `../../../../scripts/format_classpath.sh . ../../../lib/java-models-library/target/core-models.jar ../../../lib/java-models-library/target/cprover-api.jar`
 ^Generated [0-9]+ VCC\(s\), 1 remaining after simplification$

jbmc/regression/jbmc-strings/StringBuilderChars01/test.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 StringBuilderChars01
 --function StringBuilderChars01.test --unwind 10 --cp `../../../../scripts/format_classpath.sh . ../../../lib/java-models-library/target/core-models.jar ../../../lib/java-models-library/target/cprover-api.jar`
 ^EXIT=0$

jbmc/regression/jbmc-strings/StringIndexMethods01/test.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 StringIndexMethods01
 --max-nondet-string-length 1000
 ^EXIT=0$

jbmc/regression/jbmc-strings/StringIndexOf/test_thorough.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 Test
 --function Test.check --unwind 10 --max-nondet-string-length 10 --java-assume-inputs-non-null
 ^EXIT=0$

jbmc/regression/jbmc-strings/StringStartEnd01/test.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 StringStartEnd01
 --max-nondet-string-length 1000 --unwind 30
 ^EXIT=0$

jbmc/regression/jbmc-strings/StringStartEnd03/test.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 StringStartEnd03
 --max-nondet-string-length 1000 --unwind 15
 ^EXIT=10$

regression/cbmc-cover/location15/test.desc

@@ -1,4 +1,4 @@
-THOROUGH
+CORE
 main.c
 --cover location
 ^EXIT=0$
@@ -8,6 +8,10 @@ main.c
 ^\[main.coverage.3\] file main.c line 13 function main block 3.*: FAILED$
 ^\[main.coverage.4\] file main.c line 16 function main block 4.*: SATISFIED$
 ^\[foo.coverage.1\] file main.c line 5 function foo block 1.*: FAILED$
-^\*\* 3 of 5 covered \(60.0%\)
+^\*\* 3 of \d+ covered
 --
 ^warning: ignoring
+--
+This test yields 5 blocks on Linux, 60 blocks on MacOS, and 65 blocks on
+Windows. In all cases, 3 blocks are covered successfully, everything else is
+unreachable.