Split ENABLE_LEGACY_PROVIDER_JOBS into independent FTP/HARMONIE flags

Real LVGMC FTP credentials arrived today; real DMI HARMONIE
credentials haven't. The combined flag would have enabled both the
moment FTP's were ready, crash-looping the app on HARMONIE's still-
placeholder values via parMapN — caught this before it happened
(the Grib job was ~15 min from its first scheduled run). Split into
ENABLE_LVGMC_FTP_JOBS and ENABLE_HARMONIE_JOBS so each provider can
be enabled independently as its own credentials become real.

docker-compose.yml

@@ -34,7 +34,8 @@ services:
       HARMONIE_STAC_API_KEY: ${HARMONIE_STAC_API_KEY}
       HARMONIE_STAC_URL: ${HARMONIE_STAC_URL}
       ENABLE_SCHEDULED_JOBS: ${ENABLE_SCHEDULED_JOBS:-true}
-      ENABLE_LEGACY_PROVIDER_JOBS: ${ENABLE_LEGACY_PROVIDER_JOBS:-false}
+      ENABLE_LVGMC_FTP_JOBS: ${ENABLE_LVGMC_FTP_JOBS:-false}
+      ENABLE_HARMONIE_JOBS: ${ENABLE_HARMONIE_JOBS:-false}
     build:
       context: .
       dockerfile: Dockerfile.local