[KYUUBI #5914] Update layer diagram on welcome page

# 🔍 Description
## Issue References 🔗

As described.

## Describe Your Solution 🔧

- replace `User Layer` with `User Scenarios`
- realign the vertical margin of the logos in column
- larger width for better displaying
- correct StarRocks logo

## Types of changes 🔖

- [ ] Bugfix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

## Test Plan 🧪

#### Behavior Without This Pull Request ⚰️
![image](https://github.com/apache/kyuubi/assets/1935105/c8417de5-e417-4f33-921b-f7421474be8a)

#### Behavior With This Pull Request 🎉
![image](https://github.com/apache/kyuubi/assets/1935105/d5525e5b-d618-4832-87ea-590d4ffa1d5f)

#### Related Unit Tests

---

# Checklists
## 📝 Author Self Checklist

- [x] My code follows the [style guidelines](https://kyuubi.readthedocs.io/en/master/contributing/code/style.html) of this project
- [x] I have performed a self-review
- [ ] I have commented my code, particularly in hard-to-understand areas
- [x] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my feature works
- [ ] New and existing unit tests pass locally with my changes
- [x] This patch was not authored or co-authored using [Generative Tooling](https://www.apache.org/legal/generative-tooling.html)

## 📝 Committer Pre-Merge Checklist

- [ ] Pull request title is okay.
- [ ] No license issues.
- [ ] Milestone correctly set?
- [ ] Test coverage is ok
- [ ] Assignees are selected.
- [ ] Minimum number of approvals
- [ ] No changes are requested

**Be nice. Be informative.**

Closes #5914 from bowenliang123/layer-logo2.

Closes #5914

238bc9d [Bowen Liang] update layer
77811b8 [Bowen Liang] update layer
7f613e5 [Bowen Liang] Update .gitignore
a4b0b95 [Bowen Liang] update
16ebe6e [Bowen Liang] update layer

Authored-by: Bowen Liang <[email protected]>
Signed-off-by: Bowen Liang <[email protected]>

.gitignore

@@ -80,3 +80,7 @@ conf/kyuubi-env.sh
 kyuubi-server/gen
 kyuubi-server/src/main/antlr4/org/apache/kyuubi/sql/*.tokens
 kyuubi-server/src/main/antlr4/org/apache/kyuubi/sql/gen/
+
+# For draw.io
+.$*.bkp
+.$*.dtmp