Tidy help/message strings in EnginX UI

A couple of things found in #20587 that didn't seem worthy of opening a
ticket for someone else to do.

qt/scientific_interfaces/EnggDiffraction/EnggDiffractionPresenter.cpp

@@ -354,8 +354,8 @@ void EnggDiffractionPresenter::ProcessCropCalib() {
     if (m_view->currentCalibSpecNos().empty() &&
         specNoNum == BankMode::SPECNOS) {
       throw std::invalid_argument(
-          "The Spectrum Nos cannot be empty, must be a"
-          "valid range or a Bank Name can be selected instead");
+          "The Spectrum Numbers field cannot be empty, must be a "
+          "valid range or a Bank Name can be selected instead.");
     }
   } catch (std::invalid_argument &ia) {
     m_view->userWarning("Error in the inputs required for cropped calibration",
@@ -1326,8 +1326,9 @@ void EnggDiffractionPresenter::inputChecksBeforeFocusCropped(
   }
 
   if (specNos.empty()) {
-    throw std::invalid_argument("The list of spectrum Nos cannot be empty when "
-                                "focusing in 'cropped' mode.");
+    throw std::invalid_argument(
+        "The Spectrum Numbers field cannot be empty when "
+        "focusing in 'cropped' mode.");
   }
 
   inputChecksBanks(banks);

qt/scientific_interfaces/EnggDiffraction/EnggDiffractionQtTabFitting.ui

@@ -417,7 +417,7 @@
             </font>
            </property>
            <property name="toolTip">
-            <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Shift+ Left Click&lt;/span&gt; to select peak then click &lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Add Peak &lt;/span&gt;to add to list of peaks.&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Left Click+Drag &lt;/span&gt;to zoom into an area within the peak display.&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Left Click&lt;/span&gt; to return to original zoom size.&lt;/p&gt;&lt;p&gt;Selected peaks can be removed from the top of the interface&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+            <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Shift+ Left Click&lt;/span&gt; to select peak then click &lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Add Peak &lt;/span&gt;to add to list of peaks.&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Left Click+Drag &lt;/span&gt;to zoom into an area within the peak display.&lt;/p&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; font-style:italic;&quot;&gt;Right Click&lt;/span&gt; to return to original zoom size.&lt;/p&gt;&lt;p&gt;Selected peaks can be removed from the top of the interface&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
            </property>
            <property name="styleSheet">
             <string notr="true">border: 0px;