Python: Consistenly use "a user-provided value"

ReflectedXss was the only query that used it with the "a"

Author: RasmusWL

python/ql/src/Security/CWE-079/ReflectedXss.ql

@@ -34,4 +34,4 @@ class ReflectedXssConfiguration extends TaintTracking::Configuration {
 from ReflectedXssConfiguration config, TaintedPathSource src, TaintedPathSink sink
 where config.hasFlowPath(src, sink)
 select sink.getSink(), src, sink, "Cross-site scripting vulnerability due to $@.", src.getSource(),
-    "user-provided value"
+    "a user-provided value"

python/ql/src/Security/CWE-094/CodeInjection.ql

@@ -34,4 +34,4 @@ class CodeInjectionConfiguration extends TaintTracking::Configuration {
 from CodeInjectionConfiguration config, TaintedPathSource src, TaintedPathSink sink
 where config.hasFlowPath(src, sink)
 select sink.getSink(), src, sink, "$@ flows to here and is interpreted as code.", src.getSource(),
-    "User-provided value"
+    "A user-provided value"

python/ql/test/query-tests/Security/CWE-079/ReflectedXss.expected

@@ -6,4 +6,4 @@ edges
 | reflected_xss.py:8:44:8:53 | externally controlled string | reflected_xss.py:8:26:8:53 | externally controlled string |
 | reflected_xss.py:8:44:8:53 | externally controlled string | reflected_xss.py:8:26:8:53 | externally controlled string |
 #select
-| reflected_xss.py:8:26:8:53 | BinaryExpr | reflected_xss.py:7:18:7:29 | dict of externally controlled string | reflected_xss.py:8:26:8:53 | externally controlled string | Cross-site scripting vulnerability due to $@. | reflected_xss.py:7:18:7:29 | Attribute | user-provided value |
+| reflected_xss.py:8:26:8:53 | BinaryExpr | reflected_xss.py:7:18:7:29 | dict of externally controlled string | reflected_xss.py:8:26:8:53 | externally controlled string | Cross-site scripting vulnerability due to $@. | reflected_xss.py:7:18:7:29 | Attribute | a user-provided value |

python/ql/test/query-tests/Security/CWE-094/CodeInjection.expected

@@ -10,4 +10,4 @@ edges
 | code_injection.py:7:34:7:43 | externally controlled string | code_injection.py:7:14:7:44 | externally controlled string |
 | code_injection.py:7:34:7:43 | externally controlled string | code_injection.py:7:14:7:44 | externally controlled string |
 #select
-| code_injection.py:7:14:7:44 | Attribute() | code_injection.py:4:20:4:26 | django.request.HttpRequest | code_injection.py:7:14:7:44 | externally controlled string | $@ flows to here and is interpreted as code. | code_injection.py:4:20:4:26 | request | User-provided value |
+| code_injection.py:7:14:7:44 | Attribute() | code_injection.py:4:20:4:26 | django.request.HttpRequest | code_injection.py:7:14:7:44 | externally controlled string | $@ flows to here and is interpreted as code. | code_injection.py:4:20:4:26 | request | A user-provided value |