fix: grpc-web trailers

[sheharyaar]

Description

Fixes #10573 and closes #10613

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[sheharyaar]

This PR is not yet complete, need to add some features.
@Affanmir, please checkout this PR and confirm if this fixes your issue ?

[Vacant2333]

@sheharyaar hello~ have u test on your enviorment? u can add some testcase that can help us to review~~

[sheharyaar]

@Vacant2333 , I have added test-cases, please approve workflow

[monkeyDluffy6017]

@sheharyaar Is this pr ready?

[sheharyaar]

Yes, the PR is ready @monkeyDluffy6017

[Affanmir]

This PR is not yet complete, need to add some features. @Affanmir, please checkout this PR and confirm if this fixes your issue ?

Missing trailers issue fixed but path based testing cannot be done until the cors issue is resolved.

Access to XMLHttpRequest at 'https://XXXXXXXX/RANDOM.RANDOM.SERVICENAME.service.ServiceExternal/SERVICEMETHOF' from origin 'http://localhost:8080/' has been blocked by CORS policy: Request header field REDACTED_FIELD is not allowed by Access-Control-Allow-Headers in preflight response.
SUBDOMAON.DOMAIN/RANDOM.RANDOM.SERVICENAME.service.ServiceExternal/SERVICEMETHOD:1

The issue persistents even when using cors plugin alongside this plugin. Please replicate on your end

[Vacant2333]

hi, the ci was failed mostly, u can merge the master after the pr get merged~ it will fix it

[Vacant2333]

r u ready to review and merge now? @shreemaan-abhishek can u help take a look~

[sheharyaar]

Yes, I am ready

[shreemaan-abhishek]

https://github.com/apache/apisix/pull/10851/files#r1463630260

[Revolyssup]

please fix ci

[sheharyaar]

I am having issues with this. Locally it works fine for me. I need help with this.