Add second try for index path with instrument shortname

If the path for the instrument index file was not found with instrument's name,
try again with instrument's shortname.
Solves case on IDAaaS where "ENGINX" (shortname) is the name of the folder
instead of "ENGIN-X" (name).
This commit can be reverted in the future if IDAaaS updates name to "ENGIN-X".

Framework/API/inc/MantidAPI/ISISInstrumentDataCache.h

@@ -10,6 +10,7 @@
 // Includes
 //----------------------------------------------------------------------
 #include "MantidAPI/DllConfig.h"
+#include "MantidKernel/ConfigService.h"
 #include <string>
 
 namespace Mantid {
@@ -21,7 +22,8 @@ class MANTID_API_DLL ISISInstrumentDataCache {
   std::string getFileParentDirectoryPath(const std::string &filename) const;
 
 private:
-  std::pair<std::string, std::string> validateInstrumentAndNumber(const std::string &filename) const;
+  std::pair<Mantid::Kernel::InstrumentInfo, std::string> validateInstrumentAndNumber(const std::string &filename) const;
+  std::string makeIndexFilePath(const std::string &instrumentName) const;
   std::pair<std::string, std::string> splitIntoInstrumentAndNumber(const std::string &filename) const;
   std::string m_dataCachePath;
 };

Framework/API/src/ISISInstrumentDataCache.cpp

@@ -14,13 +14,19 @@ Mantid::Kernel::Logger g_log("ISISInstrumentDataCache");
 std::string Mantid::API::ISISInstrumentDataCache::getFileParentDirectoryPath(const std::string &fileName) const {
   g_log.debug() << "ISISInstrumentDataCache::getFileParentDirectoryPath(" << fileName << ")" << std::endl;
 
-  auto [instrName, runNumber] = validateInstrumentAndNumber(fileName);
+  auto [instrumentInfo, runNumber] = validateInstrumentAndNumber(fileName);
+  std::string instrName = instrumentInfo.name();
 
   // Open index json file
-  std::string jsonPath = m_dataCachePath + "/" + instrName + "/" + instrName + "_index.json";
+  std::string jsonPath = makeIndexFilePath(instrName);
   std::ifstream ifstrm{jsonPath};
-  if (!ifstrm) {
-    throw std::invalid_argument("Could not open index file: " + jsonPath);
+  if (!ifstrm.is_open()) { // Try again with shortname
+    instrName = instrumentInfo.shortName();
+    jsonPath = makeIndexFilePath(instrName);
+    ifstrm.open(jsonPath);
+    if (!ifstrm.is_open()) {
+      throw std::invalid_argument("Could not open index file: " + jsonPath);
+    }
   }
 
   // Read directory path from json file
@@ -39,7 +45,7 @@ std::string Mantid::API::ISISInstrumentDataCache::getFileParentDirectoryPath(con
   return dirPath;
 }
 
-std::pair<std::string, std::string>
+std::pair<Mantid::Kernel::InstrumentInfo, std::string>
 Mantid::API::ISISInstrumentDataCache::validateInstrumentAndNumber(const std::string &fileName) const {
 
   // Check if suffix eg. -add is present in filename
@@ -57,12 +63,18 @@ Mantid::API::ISISInstrumentDataCache::validateInstrumentAndNumber(const std::str
   runNumber.erase(0, runNumber.find_first_not_of('0')); // Remove padding zeros
 
   try { // Expand instrument name
-    instrName = FileFinder::Instance().getInstrument(instrName, false).name();
+    auto instrumentInfo = FileFinder::Instance().getInstrument(instrName, false);
+    return std::pair(instrumentInfo, runNumber);
+
   } catch (const Kernel::Exception::NotFoundError &) {
     throw std::invalid_argument("Instrument name not recognized.");
   }
+}
 
-  return std::pair(instrName, runNumber);
+std::string Mantid::API::ISISInstrumentDataCache::makeIndexFilePath(const std::string &instrumentName) const {
+  g_log.debug() << "ISISInstrumentDataCache::makeIndexFilePath(" << instrumentName << ")" << std::endl;
+  std::string indexFilePath = m_dataCachePath + "/" + instrumentName + "/" + instrumentName + "_index.json";
+  return indexFilePath;
 }
 
 std::pair<std::string, std::string>