Merge pull request github#6893 from geoffw0/nullterm

C++: Disable the two null termination queries enabled by 6794.

Author: MathiasVP

cpp/ql/src/Likely Bugs/Memory Management/ImproperNullTermination.ql

@@ -5,7 +5,6 @@
  * @kind problem
  * @id cpp/improper-null-termination
  * @problem.severity warning
- * @precision medium
  * @security-severity 7.8
  * @tags security
  *       external/cwe/cwe-170

cpp/ql/src/Security/CWE/CWE-170/ImproperNullTerminationTainted.ql

@@ -5,7 +5,6 @@
  * @kind problem
  * @id cpp/user-controlled-null-termination-tainted
  * @problem.severity warning
- * @precision medium
  * @security-severity 10.0
  * @tags security
  *       external/cwe/cwe-170