Revert "additional env var to force saying we're in tty"

This reverts commit c70f3d2.

Author: DougGregor

Tests/JavaKitTests/BasicRuntimeTests.swift

@@ -16,7 +16,6 @@ import JavaKit
 import JavaKitNetwork
 import JavaKitVM
 import Testing
-import Foundation
 
 #if os(Linux)
 import Glibc
@@ -95,10 +94,7 @@ var isLinux: Bool {
 
 /// Whether we're running on MacOS in an interactive terminal session.
 var isMacOSTerminal: Bool {
-  isMacOS && (
-    isatty(STDOUT_FILENO) == 1 ||
-    ProcessInfo.processInfo.environment["IS_TTY"] != nil // since 'swift test' still sometimes hides the fact we're in tty
-  )
+  isMacOS && isatty(STDOUT_FILENO) == 1
 }
 
 /// Whether we're running on MacOS.