test: drop all the forced use of bundle2

Using bundle2 during exchange is now the default, we do not need all this
explicit enabling of bundle2 exchange in test anymore.

tests/test-http.t

@@ -1,12 +1,5 b''
 #require serve
 
-  $ cat << EOF >> $HGRCPATH
-  > [experimental]
-  > # drop me once bundle2 is the default,
-  > # added to get test change early.
-  > bundle2-exp = True
-  > EOF
-
   $ hg init test
   $ cd test
   $ echo foo>foo

tests/test-pull-http.t

@@ -1,12 +1,5 b''
 #require killdaemons
 
-  $ cat << EOF >> $HGRCPATH
-  > [experimental]
-  > # drop me once bundle2 is the default,
-  > # added to get test change early.
-  > bundle2-exp = True
-  > EOF
-
   $ hg init test
   $ cd test
   $ echo a > a

tests/test-push-http.t

@@ -1,12 +1,5 b''
 #require killdaemons
 
-  $ cat << EOF >> $HGRCPATH
-  > [experimental]
-  > # drop me once bundle2 is the default,
-  > # added to get test change early.
-  > bundle2-exp = True
-  > EOF
-
   $ hg init test
   $ cd test
   $ echo a > a

tests/test-ssh.t

@@ -1,10 +1,3 b''
-  $ cat << EOF >> $HGRCPATH
-  > [experimental]
-  > # drop me once bundle2 is the default,
-  > # added to get test change early.
-  > bundle2-exp = True
-  > EOF
-
 
 This test tries to exercise the ssh functionality with a dummy script