Tweak parser recovery (#8819)

Closes #8722

Fixes error message for:

```
START TRANSACTION ISOLATION REPEATABLEREAD, NOT DEFERRABLE;
                           ^ Expected "SERIALIZABLE"
```

Author: aljazerzen

edb/edgeql-parser/src/parser/mod.rs

@@ -586,7 +586,7 @@ fn injection_cost(kind: &Kind) -> u16 {
         // Manual keyword tweaks to encourage some error messages and discourage others.
         Keyword(keywords::Keyword(
             "delete" | "update" | "migration" | "role" | "global" | "administer" | "future"
-            | "database", //  | "if" | "group",
+            | "database" | "serializable" | "REPEATABLE" | "NOT", //  | "if" | "group",
         )) => 100,
         Keyword(keywords::Keyword("insert" | "module" | "extension" | "branch")) => 20,
         Keyword(keywords::Keyword("select" | "property" | "type")) => 10,

tests/test_edgeql_syntax.py

@@ -6433,6 +6433,14 @@ def test_edgeql_syntax_transaction_06(self):
         START TRANSACTION ISOLATION SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
         """
 
+    @tb.must_fail(errors.EdgeQLSyntaxError,
+                  r"Unexpected 'REPEATABLEREAD'",
+                  line=2, col=37)
+    def test_edgeql_syntax_transaction_07(self):
+        """
+        START TRANSACTION ISOLATION REPEATABLEREAD, NOT DEFERRABLE;
+        """
+
     def test_edgeql_syntax_describe_01(self):
         """
         DESCRIBE SCHEMA AS DDL;