[BUG] IPv6 upstream addresses are parsed incorrectly by colon splitting #6442

Current Behavior

Several admin/common runtime paths parse upstream URLs by splitting on :. This breaks valid IPv6 upstream addresses.

Evidence:

• shenyu-common/src/main/java/org/apache/shenyu/common/utils/UpstreamCheckUtils.java:67-73
• shenyu-admin/src/main/java/org/apache/shenyu/admin/service/manager/impl/LoadServiceDocEntryImpl.java:153-158
• shenyu-admin/src/main/java/org/apache/shenyu/admin/transfer/DiscoveryTransfer.java:352-361

Examples:

hostPort = StringUtils.split(http[1], Constants.COLONS);
...
String[] upstreamUrlArr = discoveryUpstreamData.getUrl().split(":");
...
.map(url -> url.split(":", 2))

For valid IPv6 literals such as [2001:db8::1]:8080 or http://[2001:db8::1]:8080, colon splitting truncates the host and/or attempts to parse part of the IPv6 literal as a port. That can produce a failed health check, wrong discovery upstream data, or NumberFormatException.

Expected Behavior

Valid IPv6 upstream addresses should be parsed with URI/host-port aware logic and should work in health checks, discovery conversion, and API document loading.

Steps To Reproduce

Use an upstream URL such as:

[2001:db8::1]:8080
http://[2001:db8::1]:8080

Then trigger one of these paths:

• upstream health check via UpstreamCheckUtils.checkUrl(...)
• discovery upstream conversion via DiscoveryTransfer.mapToDiscoveryUpstreamData(...)
• API document instance loading via LoadServiceDocEntryImpl.getInstances2(...)

Suggested Fix

Use java.net.URI or a host-port parser that supports bracketed IPv6 literals. Avoid raw split(":") for URLs or host:port strings.