tests: remove initial bundle2 enabling in various bundle2 tests

tests: remove initial bundle2 enabling in various bundle2 tests

Bundle 2 is enable by default since 3.6 so we don't need this anymore.

The remaining use of 'experimental.bundle2-exp' are there to test legacy behavior
with bundle 1. Future patches will introduce a way outside of experimental to
test that.

--- a/tests/test-bundle2-exchange.t	Tue Aug 02 15:44:51 2016 +0200
+++ b/tests/test-bundle2-exchange.t	Tue Aug 02 14:54:06 2016 +0200
@@ -16,7 +16,6 @@
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > evolution=createmarkers,exchange
-  > bundle2-exp=True
   > bundle2-output-capture=True
   > [ui]
   > ssh=python "$TESTDIR/dummyssh"

--- a/tests/test-bundle2-format.t	Tue Aug 02 15:44:51 2016 +0200
+++ b/tests/test-bundle2-format.t	Tue Aug 02 14:54:06 2016 +0200
@@ -227,7 +227,6 @@
   > [extensions]
   > bundle2=$TESTTMP/bundle2.py
   > [experimental]
-  > bundle2-exp=True
   > evolution=createmarkers
   > [ui]
   > ssh=python "$TESTDIR/dummyssh"

--- a/tests/test-bundle2-multiple-changegroups.t	Tue Aug 02 15:44:51 2016 +0200
+++ b/tests/test-bundle2-multiple-changegroups.t	Tue Aug 02 14:54:06 2016 +0200
@@ -33,8 +33,6 @@
   > EOF
 
   $ cat >> $HGRCPATH << EOF
-  > [experimental]
-  > bundle2-exp=True
   > [ui]
   > logtemplate={rev}:{node|short} {phase} {author} {bookmarks} {desc|firstline}
   > EOF

--- a/tests/test-bundle2-pushback.t	Tue Aug 02 15:44:51 2016 +0200
+++ b/tests/test-bundle2-pushback.t	Tue Aug 02 14:54:06 2016 +0200
@@ -50,8 +50,6 @@
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > bundle2=$TESTTMP/bundle2.py
-  > [experimental]
-  > bundle2-exp = True
   > EOF
 
 Without config

--- a/tests/test-bundle2-remote-changegroup.t	Tue Aug 02 15:44:51 2016 +0200
+++ b/tests/test-bundle2-remote-changegroup.t	Tue Aug 02 14:54:06 2016 +0200
@@ -78,8 +78,6 @@
   $ cat dumb.pid >> $DAEMON_PIDS
 
   $ cat >> $HGRCPATH << EOF
-  > [experimental]
-  > bundle2-exp=True
   > [ui]
   > ssh=python "$TESTDIR/dummyssh"
   > logtemplate={rev}:{node|short} {phase} {author} {bookmarks} {desc|firstline}