Remove `DES-CBC3-SHA` from TLS Ciphers

I've scanned one of my setup lately and nmap is reporting use of unsecure cipher:
```
nmap -Pn -p 443 --script ssl-enum-ciphers my.dev.setup.com
Starting Nmap 7.95 ( https://nmap.org ) at 2025-06-12 15:40 PDT
Nmap scan report for my.dev.setup.com (1.2.3.4)
Host is up (0.69s latency).

PORT STATE SERVICE
443/tcp open https
| ssl-enum-ciphers:
| TLSv1.2:
| ciphers:
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (ecdh_x25519) - A
| TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (ecdh_x25519) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (ecdh_x25519) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (ecdh_x25519) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (ecdh_x25519) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (ecdh_x25519) - A
| TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C
| compressors:
| NULL
| cipher preference: server
| warnings:
| 64-bit block cipher 3DES vulnerable to SWEET32 attack
| TLSv1.3:
| ciphers:
| TLS_AKE_WITH_AES_256_GCM_SHA384 (ecdh_x25519) - A
| TLS_AKE_WITH_CHACHA20_POLY1305_SHA256 (ecdh_x25519) - A
| TLS_AKE_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A
| cipher preference: server
|_ least strength: C
```
Is there any specific reason that ApiSix has to use 3DES? Can this be removed?

I have prepared a PR covering this and also adding easy way to configure list of supported ciphers by ApiSix https://github.com/apache/apisix-helm-chart/pull/834 - maybe this could be merged?

Start by reviewing the current APISIX Helm chart TLS cipher settings and the referenced PR #834, since the issue names no files or tests. Confirm how the chart configures supported ciphers, then verify that DES-CBC3-SHA is removed and the proposed cipher-list configuration works as intended.

Written by the indexing model from the issue text.