PMM-15360: Regenerate the server/v1 swagger and JSON client for om_enabled

make gen does more than buf generate -- it also regenerates the
swagger/OpenAPI JSON (api/server/v1/json/v1.json, the merged
api/swagger/swagger*.json) and the generated JSON API client
(api/server/v1/json/client/server_service/*.go) from the same proto.
The earlier commit only ran buf generate directly and hand-curated its
output against unrelated toolchain drift elsewhere in api/, which
missed these -- they're make gen's job, not buf generate's.

Also picks up the same protoc-gen-go import-grouping drift on
server.pb.go/server.pb.validate.go that affects unrelated proto
packages across the tree; taking make gen's own output here (rather my
earlier hand-curated one) is what actually matches what CI's own gen
step produces, so this and CI won't disagree again.

The generated client's field names are OmEnabled/EnableOm here,
matching this branch's own api/Makefile: --additional-initialism=om
was added to the swagger client generator's flag list by
PMM-15326-om-api, but that commit hasn't reached this branch's base
(PMM-15299-open-manager) yet, so "om" isn't a registered initialism
here and go-swagger capitalizes it as an ordinary word. Branches that
already have that flag (PMM-15326-om-backend and its descendants) will
correctly want OMEnabled/EnableOM instead -- each PR's generated code
has to match its own base's Makefile, not a single "right" answer
across the stack.

Found because CI's "make gen; git diff --exit-code" check failed on
this exact mismatch, on all three of this ticket's PRs.

Signed-off-by: Pawel Lebioda <pawel.lebioda@percona.com>

Author: plebioda

api/server/v1/json/client/server_service/change_settings_responses.go

@@ -311,6 +311,11 @@
                       "description": "True if Query Analytics for PMM's internal PG database is enabled.",
                       "type": "boolean",
                       "x-order": 17
+                    },
+                    "om_enabled": {
+                      "description": "True if OpenManager is enabled.",
+                      "type": "boolean",
+                      "x-order": 18
                     }
                   },
                   "x-order": 0
@@ -488,6 +493,12 @@
                   "type": "boolean",
                   "x-nullable": true,
                   "x-order": 13
+                },
+                "enable_om": {
+                  "description": "Enable OpenManager.",
+                  "type": "boolean",
+                  "x-nullable": true,
+                  "x-order": 14
                 }
               }
             }
@@ -629,6 +640,11 @@
                       "description": "True if Query Analytics for PMM's internal PG database is enabled.",
                       "type": "boolean",
                       "x-order": 17
+                    },
+                    "om_enabled": {
+                      "description": "True if OpenManager is enabled.",
+                      "type": "boolean",
+                      "x-order": 18
                     }
                   },
                   "x-order": 0
@@ -729,6 +745,11 @@
                       "description": "True if Access Control is enabled.",
                       "type": "boolean",
                       "x-order": 7
+                    },
+                    "om_enabled": {
+                      "description": "True if OpenManager is enabled.",
+                      "type": "boolean",
+                      "x-order": 8
                     }
                   },
                   "x-order": 0