Revert http client changes (#18892)

These proved to be too unstable. Will restore these changes once the issues have been fixed.

Release Notes:

- N/A

crates/zed/Cargo.toml

@@ -57,6 +57,7 @@ http_client.workspace = true
 image_viewer.workspace = true
 inline_completion_button.workspace = true
 install_cli.workspace = true
+isahc_http_client.workspace = true
 journal.workspace = true
 language.workspace = true
 language_model.workspace = true
@@ -107,7 +108,6 @@ theme.workspace = true
 theme_selector.workspace = true
 time.workspace = true
 ui.workspace = true
-ureq_client.workspace = true
 url.workspace = true
 urlencoding = "2.1.2"
 util.workspace = true