Fix reno for RC1

This is a bus for all reno problems we see with the relnotes :

* Change Id25bd4870c6e2fda08dc0177b7ed61a8a6091838 was having
a formatting problem with not retaining the newlines, and also
was mentioning "Nove" :-)

* Change I43ddc5164f88fb049fe49ad4672fbf09b2b1987e was using a
prelude section that is not needed because we will provide a
general prelude section (and commenting that) in the next change.

* Change I2dba71e71b1ed7cf8476e8bfe9481e84be5df128 was incorrectly
using the upgrades section while it was a deprecation.

* Change Ia6f1d8f9c7d700498b6441a6ba37fa25b2611ef8 is no longer
valid because Id7936be290b6febd18deb4c2db8ea4d678d4d9b1 has been
merged during Mitaka too.

* Change I2465e1bee618a552132d659014ea96cdbda161d6 was reverting
a reno file but due to a reno bug (see
https://review.openstack.org/#/c/293078/), the release note is
still kept in the output. Consequently, the workaround I found
is to reintroduce the same reno file with an empty content to
drop the previous content.

Note that I used the prelude section for "dropping" notes, that
prevents us to provide empty bullets for upgrade or features sections.

Change-Id: I1535aff80850fa3666da739133fc43e8579aa19b

releasenotes/notes/api-database-now-required-6245f39d36885d1c.yaml

@@ -1,8 +1,4 @@
 ---
-prelude: >
-    Nova now requires a separate API database and manual
-    intervention is required during an upgrade to Mitaka.
-
 upgrade:
   - During an upgrade to Mitaka, operators must create and initialize
     a database for the API service. Configure this in

releasenotes/notes/deprecate_pluggable_managers-ca0224bcd779454c.yaml

@@ -1,7 +1,7 @@
 ---
 deprecations:
-
-  - Nove used to support the concept that ``service managers`` were
+  - |
+    Nova used to support the concept that ``service managers`` were
     replaceable components. There are many config options where you can
     replace a manager by specifying a new class. This concept is
     deprecated in Mitaka as are the following config options.

releasenotes/notes/disable_ec2_api_by_default-0ec0946433fc7119.yaml

@@ -1,6 +1,2 @@
 ---
-upgrade:
-  - As of Kilo the in tree EC2 API is marked as deprecated.
-    The in tree EC2 API is now disabled by default. You have
-    to add ``ec2`` to the ``enabled_apis`` configuration parameter
-    if you stil want to use it.
+prelude: >

releasenotes/notes/reserved-hugepages-per-nodes-f36225d5fca807e4.yaml

@@ -0,0 +1,2 @@
+---
+prelude: >

releasenotes/notes/zookeeper-servicegroup-driver-removed-c3bcaa6f9fe976ed.yaml

@@ -1,5 +1,5 @@
 ---
-upgrade:
+deprecations:
   - |
     The Zookeeper Service Group driver has been removed.