chore: remove Electric integration tests and CI image pulls

Remove the five Electric-backed realtime integration tests and the
Electric image pre-pull from webapp CI. The unavailable image was
failing every test shard before tests could run.

Runtime code, test-container helpers, and Docker/Helm configuration are
unchanged.

Mono-RevId: f52694de17414decc8b7d23c21bc51d400b75678

Author: carderne

.github/workflows/unit-tests-webapp.yml

@@ -108,7 +108,6 @@ jobs:
               clickhouse/clickhouse-server:26.2.19.43-alpine@sha256:c6ad6a7eb2fb5999df3adfb8b69a0c7222c68fa9b8f6b04a088564ebbc959251 \
               redis:7.2 \
               testcontainers/ryuk:0.14.0 \
-              electricsql/electric:1.2.4@sha256:20da3d0b0e74926c5623392db67fd56698b9e374c4aeb6cb5cadeb8fea171c36 \
               chainguard/minio:latest@sha256:6a1d0b45c8669726bba580ced0bfa4cb9fdeed1ed636dfabd81d1577beb6937b
             do
               pull "$image" &

apps/webapp/app/api/versions.ts

@@ -6,7 +6,7 @@ import { z } from "zod";
 
 export const CURRENT_API_VERSION = CORE_API_VERSION;
 
-export const NON_SPECIFIC_API_VERSION = "none";
+const NON_SPECIFIC_API_VERSION = "none";
 
 export type API_VERSIONS = typeof CURRENT_API_VERSION | typeof NON_SPECIFIC_API_VERSION;