docs: Make JSON valid

Pygments 2.7.x is stricter in how it validates JSON escapes, aligning it
closer with the spec [1]. Turns out we have some invalid JSON in our
docs, meaning builds are now failing with the following error:

  doc/source/user/metadata.rst:262: WARNING: Could not lex literal_block
  as "json". Highlighting skipped.

Resolve this.

[1] 9514e794e0

Change-Id: Ic50e29e9c7817744ad0b4f9de309aa3e96a09505
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

doc/source/user/metadata.rst

@@ -262,27 +262,11 @@ example:
 .. code-block:: json
 
    {
-      "random_seed": "yu5ZnkqF2CqnDZVAfZgarGLoFubhcK5wHG4fcNfVZEtie/bTV8k2dDXK\
-                      C7krP2cjp9A7g9LIWe5+WSaZ3zpvQ03hp/4mMNy9V1U/mnRMZyQ3W4Fn\
-                      Nex7UP/0Smjb9rVzfUb2HrVUCN61Yo4jHySTd7UeEasF0nxBrx6NFY6e\
-                      KRoELGPPr1S6+ZDcDT1Sp7pRoHqwVbzyJZc80ICndqxGkZOuvwDgVKZD\
-                      B6O3kFSLuqOfNRaL8y79gJizw/MHI7YjOxtPMr6g0upIBHFl8Vt1VKjR\
-                      s3zB+c3WkC6JsopjcToHeR4tPK0RtdIp6G2Bbls5cblQUAc/zG0a8BAm\
-                      p6Pream9XRpaQBDk4iXtjIn8Bf56SCANOFfeI5BgBeTwfdDGoM0Ptml6\
-                      BJQiyFtc3APfXVVswrCq2SuJop+spgrpiKXOzXvve+gEWVhyfbigI52e\
-                      l1VyMoyZ7/pbdnX0LCGHOdAU8KRnBoo99ZOErv+p7sROEIN4Yywq/U/C\
-                      xXtQ5BNCtae389+3yT5ZCV7fYzLYChgDMJSZ9ds9fDFIWKmsRu3N+wUg\
-                      eL4klxAjRgzQ7MMlap5kppnIYRxXVy0a5j1qOaBAzJB5LLJ7r3/Om38x\
-                      Z4+XGWjqd6KbSwhUVs1aqzxpep1Sp3nTurQCuYjgMchjslt0O5oJjh5Z\
-                      hbCZT3YUc8M=\n",
-      "uuid": "d8e02d56-2648-49a3-bf97-6be8f1204f38",
+      "random_seed": "yu5ZnkqF2CqnDZVAfZgarG...",
       "availability_zone": "nova",
       "keys": [
           {
-            "data": "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQDYVEprvtYJXVOBN0XNKV\
-                     VRNCRX6BlnNbI+USLGais1sUWPwtSg7z9K9vhbYAPUZcq8c/s5S9dg5vTH\
-                     bsiyPCIDOKyeHba4MUJq8Oh5b2i71/3BISpyxTBH/uZDHdslW2a+SrPDCe\
-                     uMMoss9NFhBdKtDkdG9zyi0ibmCP6yMdEX8Q== Generated by Nova\n",
+            "data": "ssh-rsa AAAAB3NzaC1y...== Generated by Nova\n",
             "type": "ssh",
             "name": "mykey"
           }
@@ -312,10 +296,7 @@ example:
       ],
       "project_id": "f7ac731cc11f40efbc03a9f9e1d1d21f",
       "public_keys": {
-          "mykey": "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQDYVEprvtYJXVOBN0XNKV\
-                    VRNCRX6BlnNbI+USLGais1sUWPwtSg7z9K9vhbYAPUZcq8c/s5S9dg5vTH\
-                    bsiyPCIDOKyeHba4MUJq8Oh5b2i71/3BISpyxTBH/uZDHdslW2a+SrPDCe\
-                    uMMoss9NFhBdKtDkdG9zyi0ibmCP6yMdEX8Q== Generated by Nova\n"
+          "mykey": "ssh-rsa AAAAB3NzaC1y...== Generated by Nova\n"
       },
       "name": "test"
    }