Update web.xml modification for auto-reconfiguration 1.0.0

This change updates the web.xml modification behavior to support auto-
reconfiguration 1.0.0.  The modification no longer makes any change to
the application context configuration XML files or Java classes.  It
now only adds three ApplicationContextInitializers to the
configuration.  In cases where there is no web.xml file, auto-
reconfiguration 1.0.0 will use a web fragment to configure itself.

[#49695439]
Merge 49695439-servlet-3 to master

[Completes #49695439]
Merge remote-tracking branch 'upstream/master'