Fix async redirect handling regression from FOLLOW_REDIRECTS default

[cursor]

Bug and impact

PR #1278 introduced FOLLOW_REDIRECTS but changed the default from "disable redirect following in async mode" to always true when unset. Async connectors such as Slack Analytics rely on the proxy intercepting 3xx responses and fetching the Location URL manually (without forwarding source Authorization headers to pre-signed download URLs). With auto-follow enabled, the HTTP client follows redirects transparently—often with auth headers attached—so the manual redirect block never runs and async imports fail or return unusable data.

ChatGPT Enterprise is protected by an explicit FOLLOW_REDIRECTS=FALSE in Terraform; Slack Analytics has environment_variables: {} and was exposed.

Root cause

// Before #1278
.setFollowRedirects(!processingContext.getAsync());

// After #1278 (regression)
.orElse(true);

Fix

Restore the prior default: when FOLLOW_REDIRECTS is unset, follow redirects in sync mode and disable them in async mode. Explicit FOLLOW_REDIRECTS still overrides.

Added asyncModeDisablesRedirectFollowingByDefault unit test to lock in the behavior.

Validation

• mvn test -pl core -Dtest=ApiDataRequestHandlerTest — 28 tests pass

Fixes

• Async redirect handling regression from Adding property config for redirect #1278

Change implications

• dependencies added/changed? no
• breaking changes? no — restores pre-Adding property config for redirect #1278 behavior for async connectors without explicit FOLLOW_REDIRECTS