refactor(providers): delete the SSH git and filesystem providers and relay-only wiring (#27644)

* refactor(providers): delete the SSH git and filesystem providers and relay-only wiring

* refactor(ssh): drop relay-protocol exports only the deleted stream readers used

---------

Co-authored-by: m4air <m4air@Mac.localdomain>

src/main/github/github-ssh-host-alias-resolution.ts

@@ -1,6 +1,5 @@
 import type { GitHubOwnerRepo } from '../../shared/github/pull-request-types'
 import { commandExecFileAsync } from '../git/runner'
-import { getSshGitProvider, getSshGitProviderGeneration } from '../providers/ssh-git-dispatch'
 import { parseWslPath } from '../wsl'
 import { resolveWithSshG } from '../ssh/ssh-g-config-resolution'
 import {
@@ -58,8 +57,7 @@ function pruneSshHostnameCache(now: number): void {
 
 function sshRuntimeCacheKey(context: SshConfigResolutionContext): string {
   if (context.connectionId) {
-    const generation = getSshGitProviderGeneration(context.connectionId)
-    return `ssh:${context.connectionId}:${generation}`
+    return `ssh:${context.connectionId}`
   }
   const distro = context.wslDistro ?? parseWslPath(context.repoPath)?.distro
   return `local:${distro?.toLowerCase() ?? 'host'}`
@@ -80,23 +78,7 @@ async function resolveSshHostnameInRuntime(
   context: SshConfigResolutionContext
 ): Promise<string | null> {
   if (context.connectionId) {
-    const provider = getSshGitProvider(context.connectionId)
-    if (!provider) {
-      return null
-    }
-    try {
-      const result = await provider.execNonInteractive(
-        'ssh',
-        ['-G', '--', host],
-        context.repoPath,
-        SSH_G_TIMEOUT_MS
-      )
-      return result.exitCode === 0 && !result.timedOut && !result.canceled
-        ? parseSshGHostname(result.stdout)
-        : null
-    } catch {
-      return null
-    }
+    return null
   }
 
   const wslDistro = context.wslDistro ?? parseWslPath(context.repoPath)?.distro