RE #27375 Explicitly disable dynamic thread adjustment

Added done alongside setting the number of threads to ensure that
subsequent parallel regions do not change the number of threads they are
working with from the value set in the config.

Framework/Kernel/inc/MantidKernel/MultiThreaded.h

@@ -137,6 +137,7 @@ void AtomicOp(std::atomic<T> &f, T d, BinaryOp op) {
  */
 #define PARALLEL_FOR_IF(condition)                                             \
   PARALLEL_SET_THREADS_TO_CONFIG                                               \
+  PARALLEL_SET_DYNAMIC(false);                                                 \
   PRAGMA(omp parallel for if (condition) )
 
 /** Includes code to add OpenMP commands to run the next for loop in parallel.
@@ -145,6 +146,7 @@ void AtomicOp(std::atomic<T> &f, T d, BinaryOp op) {
  */
 #define PARALLEL_FOR_NO_WSP_CHECK()                                            \
   PARALLEL_SET_THREADS_TO_CONFIG                                               \
+  PARALLEL_SET_DYNAMIC(false);                                                 \
   PRAGMA(omp parallel for)
 
 /** Includes code to add OpenMP commands to run the next for loop in parallel.
@@ -154,10 +156,12 @@ void AtomicOp(std::atomic<T> &f, T d, BinaryOp op) {
  */
 #define PARALLEL_FOR_NOWS_CHECK_FIRSTPRIVATE(variable)                         \
   PARALLEL_SET_THREADS_TO_CONFIG                                               \
+  PARALLEL_SET_DYNAMIC(false);                                                 \
   PRAGMA(omp parallel for firstprivate(variable) )
 
 #define PARALLEL_FOR_NO_WSP_CHECK_FIRSTPRIVATE2(variable1, variable2)          \
   PARALLEL_SET_THREADS_TO_CONFIG                                               \
+  PARALLEL_SET_DYNAMIC(false);                                                 \
   PRAGMA(omp parallel for firstprivate(variable1, variable2) )
 
 /** Ensures that the next execution line or block is only executed if