travis: remove "coverage", make it "torture"

The coveralls service and test coverage numbers are just too unreliable.
Removed badge from README.md as well.

Fixes #4694

.travis.yml

@@ -304,7 +304,7 @@ matrix:
           compiler: gcc
           dist: xenial
           env:
-              - T=coverage
+              - T=torture
               - OVERRIDE_CC="CC=gcc-8" OVERRIDE_CXX="CXX=g++-8"
           addons:
               apt:
@@ -538,6 +538,16 @@ script:
              coveralls --gcov /usr/bin/gcov-8 --gcov-options '\-lp' -i src -e lib -e tests -e docs -b $PWD/src
              coveralls --gcov /usr/bin/gcov-8 --gcov-options '\-lp' -e src -i lib -e tests -e docs -b $PWD/lib
         fi
+    - |
+        set -eo pipefail
+        if [ "$T" = "torture" ]; then
+             ./configure --enable-debug --disable-shared --disable-threaded-resolver --enable-code-coverage --enable-werror --enable-alt-svc --with-libssh2
+             make
+             make TFLAGS=-n test-nonflaky
+             make "TFLAGS=-n -e" test-nonflaky
+             tests="1 200 300 500 700 800 900 1000 1100 1200 1302 1400 1502 3000"
+             make "TFLAGS=-n -t $tests" test-nonflaky
+        fi
     - |
         set -eo pipefail
         if [ "$T" = "debug" ]; then

README.md

@@ -5,7 +5,6 @@
 [![Travis-CI Build Status](https://travis-ci.org/curl/curl.svg?branch=master)](https://travis-ci.org/curl/curl)
 [![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/l1vv31029huhf4g4?svg=true)](https://ci.appveyor.com/project/curlorg/curl)
 [![Cirrus Build Status](https://api.cirrus-ci.com/github/curl/curl.svg?branch=master)](https://cirrus-ci.com/github/curl/curl)
-[![Coverage Status](https://coveralls.io/repos/github/curl/curl/badge.svg)](https://coveralls.io/github/curl/curl)
 [![Backers on Open Collective](https://opencollective.com/curl/backers/badge.svg)](#backers)
 [![Sponsors on Open Collective](https://opencollective.com/curl/sponsors/badge.svg)](#sponsors)
 [![Language Grade: C/C++](https://img.shields.io/lgtm/grade/cpp/g/curl/curl.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/curl/curl/context:cpp)