Update welcome screen panel illustrations (#5394)

### What

- Closes #4961

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/5394/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5394/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/5394/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5394)
- [Docs
preview](https://rerun.io/preview/3231306a2d157645aad657bd8cbeeb1141682a69/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/3231306a2d157645aad657bd8cbeeb1141682a69/examples)
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crates/re_ui/src/icons.rs

@@ -147,20 +147,15 @@ pub const STORE: Icon = Icon::new("store", include_bytes!("../data/icons/store.p
 
 pub const WELCOME_SCREEN_CONFIGURE: Icon = Icon::new(
     "welcome_screen_configure",
-    include_bytes!("../data/images/onboarding-configure.png"),
+    include_bytes!("../data/images/configure-card.png"),
 );
 
 pub const WELCOME_SCREEN_LIVE_DATA: Icon = Icon::new(
     "welcome_screen_live_data",
-    include_bytes!("../data/images/onboarding-live-data.png"),
+    include_bytes!("../data/images/live-data-card.png"),
 );
 
 pub const WELCOME_SCREEN_RECORDED_DATA: Icon = Icon::new(
     "welcome_screen_recorded_data",
-    include_bytes!("../data/images/onboarding-recorded-data.png"),
-);
-
-pub const WELCOME_SCREEN_EXAMPLES: Icon = Icon::new(
-    "welcome_screen_examples",
-    include_bytes!("../data/images/onboarding-examples.jpg"),
+    include_bytes!("../data/images/recorded-data-card.png"),
 );

crates/re_viewer/src/ui/welcome_screen/welcome_section.rs

@@ -179,7 +179,7 @@ fn onboarding_content_ui(ui: &mut Ui, command_sender: &CommandSender, accepts_co
 
     let panel_count = panels.len();
 
-    const MAX_COLUMN_WIDTH: f32 = 255.0;
+    const MAX_COLUMN_WIDTH: f32 = 280.0;
     const MIN_COLUMN_WIDTH: f32 = 164.0;
 
     let grid_spacing = egui::vec2(12.0, 16.0);