Merge bitcoin/bitcoin#13533: [tests] Reduced number of validations in tx_validationcache_tests

c3e111a7da Reduced number of validations in `tx_validationcache_tests` to keep the run time reasonable. (lucash-dev)

Pull request description:

  Following a suggestion in the comments, changed `ValidateCheckInputsForAllFlags` from testing all possible flag combinations to testing a random subset. Also created a new enum constant for the highest flag, so that this test doesn’t keep testing an incomplete subset in case a new flag is added.

  Timing for `checkinputs_test`:
  ```
  Before:   6.8s
  After:    3.7s
  ----------------
  Saved:    3.1s (45%)
  ```

  This PR was split from #13050. Also see #10026.

ACKs for top commit:
  leonardojobim:
    tACK c3e111a7da.
  kallewoof:
    ACK c3e111a7da
  theStack:
    re-ACK c3e111a7da

Tree-SHA512: bef49645bdd4f61ec73cc77a9f028b95d9856db9446d2e7fc9a48867a6f0e94c2c9f150cb771a30fe852db0efb0a1bd15d38b00d712651793ccb59ff6157a7b4

src/script/interpreter.h

@@ -139,6 +139,10 @@ enum : uint32_t {
 
     // Making unknown public key versions (in BIP 342 scripts) non-standard
     SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE = (1U << 20),
+
+    // Constants to point to the highest flag in use. Add new flags above this line.
+    //
+    SCRIPT_VERIFY_END_MARKER
 };
 
 bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);