Switch code coverage system to CodeCov (#13297)

platform/linux/scripts/coveralls.sh

@@ -1,28 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-set -o pipefail
-
-command -v lcov 2> /dev/null || {
-    echo "Aborting: lcov not found."
-    exit 1
-}
-
-# Collect coverage data and save it into coverage.info
-lcov \
-    --quiet \
-    --capture \
-    --no-external \
-    --gcov-tool "gcov-5" \
-    --directory "src/mbgl" \
-    --directory "platform" \
-    --directory "include/mbgl" \
-    --directory "build/linux-x86_64/${BUILDTYPE}" \
-    --base-directory "build/linux-x86_64/${BUILDTYPE}" \
-    --output-file "build/linux-x86_64/${BUILDTYPE}/coverage.info"
-
-coveralls-lcov \
-    --service-name="${COVERALLS_SERVICE_NAME}" \
-    --repo-token="${COVERALLS_REPO_TOKEN}" \
-    --service-job-id="${CIRCLE_BUILD_NUM}" \
-    "build/linux-x86_64/${BUILDTYPE}/coverage.info"