fix: set CLOUDSDK_PROXY_TYPE=http instead of https for gcloud

[javabrett]

Problem

sandbox-utils.ts sets CLOUDSDK_PROXY_TYPE=https when configuring the Google Cloud SDK proxy, but https is not a valid value for that property. Every gcloud command inside the sandbox fails immediately with:

ERROR: (gcloud.projects.list) Invalid value for property [proxy/type]:
The proxy type property value [https] is not valid.
Possible values: [http, http_no_tunnel, socks4, socks5].

The error can be reproduced directly without srt:

CLOUDSDK_PROXY_TYPE=https CLOUDSDK_PROXY_ADDRESS=localhost CLOUDSDK_PROXY_PORT=8080 gcloud projects list
ERROR: (gcloud.projects.list) Invalid value for property [proxy/type]: The proxy type property value [https] is not valid. Possible values: [http, http_no_tunnel, socks4, socks5].

With the fix:

CLOUDSDK_PROXY_TYPE=http CLOUDSDK_PROXY_ADDRESS=localhost CLOUDSDK_PROXY_PORT=8080 gcloud projects list
# works

Root cause

The srt HTTP proxy is an HTTP CONNECT proxy. Most tools (curl, requests, etc.) call this an "HTTPS proxy" because it tunnels HTTPS traffic. But gcloud's CLOUDSDK_PROXY_TYPE enum uses http to mean "HTTP CONNECT proxy" — the valid values (http, http_no_tunnel, socks4, socks5) describe the proxy protocol, not the tunnelled traffic.

The comment in the code acknowledges the intent ("Use HTTPS proxy to match other HTTP-based tools") but the value chosen doesn't match gcloud's vocabulary.

Fix

Change CLOUDSDK_PROXY_TYPE=https to CLOUDSDK_PROXY_TYPE=http and update the comment to explain why.

One-line diff:

-      envVars.push(`CLOUDSDK_PROXY_TYPE=https`)
+      envVars.push(`CLOUDSDK_PROXY_TYPE=http`)