Remove default stretchiness of infix operators U+2044, U+2215, U+007C

These are slashes and bars that make sense as non-stretchy too, with
no clear default. However, non-stretchy is more consistent with similar
symbols:

U+2223
U+2225
U+2758
U+29F5
U+2AFB
U+2AFD
U+29F8
U+29F9
U+005C

w3c/mathml#176

Author: fred-wang

unicode.xml

@@ -1815,7 +1815,7 @@ Barbara Beeton for the STIX project
             <desc>alias ISONUM verbar</desc>
          </entity>
          <font name="hlcry" pos="106"/>
-         <operator-dictionary priority="270" form="infix" stretchy="true" lspace="3" rspace="3" symmetric="true" fence="true"/>
+         <operator-dictionary priority="270" form="infix" lspace="3" rspace="3" fence="true"/>
          <operator-dictionary priority="20" form="prefix" symmetric="true" fence="true" stretchy="true" lspace="0" rspace="0"/>
          <operator-dictionary priority="20" form="postfix" symmetric="true" fence="true" stretchy="true" lspace="0" rspace="0"/>
          <description unicode="1.1">VERTICAL LINE</description>
@@ -37261,7 +37261,7 @@ Barbara Beeton for the STIX project
          <unicodedata category="Sm" combclass="0" bidi="CS" mirror="N" mathclass="B" alias="solidus"/>
          <mathlatex set="unicode-math">\fracslash</mathlatex>
          <entity id="frasl" set="xhtml1-symbol"/>
-         <operator-dictionary form="infix" stretchy="true" lspace="4" rspace="4" priority="680"/>
+         <operator-dictionary form="infix" lspace="4" rspace="4" priority="680"/>
          <description unicode="1.1">FRACTION SLASH</description>
       </character>
       <character id="U02045" dec="8261" type="other" mode="unknown">
@@ -42301,7 +42301,7 @@ Barbara Beeton for the STIX project
       <character id="U02215" dec="8725" type="other" mode="unknown">
          <unicodedata category="Sm" combclass="0" bidi="ON" mirror="Y" mathclass="B"/>
          <mathlatex set="unicode-math">\divslash</mathlatex>
-         <operator-dictionary form="infix" stretchy="true" lspace="4" rspace="4" priority="680"/>
+         <operator-dictionary form="infix" lspace="4" rspace="4" priority="680"/>
          <description unicode="1.1">DIVISION SLASH</description>
       </character>
       <character id="U02216" dec="8726" mode="math" type="binaryop">