Fix System.Net.Security.Enterprise.Tests build (#84795)

* Fix enterprise linux build

Ensure a recent lld is available on the build host

* Remove lld

As it is now installed in the ubuntu-22.04 image

* Try enabling legacy provider

* Fix legacy under [provider_sect]

src/libraries/Common/tests/System/Net/EnterpriseTests/setup/linuxclient/Dockerfile

@@ -1,4 +1,4 @@
-FROM mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-18.04
+FROM mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-22.04
 
 # Prevents dialog prompting when installing packages
 ARG DEBIAN_FRONTEND=noninteractive
@@ -8,6 +8,27 @@ COPY ./common/krb5.conf /etc/krb5.conf
 RUN apt-get update && \
     apt-get install -y --no-install-recommends krb5-user gss-ntlmssp iputils-ping dnsutils nano
 
+# Enable openssl legacy provider in system openssl config
+RUN fixOpensslConf=$(mktemp) && \
+    printf "#!/usr/bin/env sh\n\
+        sed -i '\n\
+            # Append 'legacy = legacy_sect' after 'default = default_sect' under [provider_sect]
+            /^default = default_sect/a legacy = legacy_sect\n\
+            # Search for [default_sect]
+            /\[default_sect\]/ {\n\
+                # Go to next line
+                n\n\
+                # Uncomment '# activate = 1'
+                s/# //\n\
+                # Append new [legacy_sect], with 'activate = 1'
+                a\n\
+                a [legacy_sect]\n\
+                a activate = 1\n\
+            }\n\
+            ' /etc/ssl/openssl.cnf\n" > $fixOpensslConf && \
+    sh $fixOpensslConf && \
+    rm $fixOpensslConf
+
 # Set environment variable to turn on enterprise tests
 ENV DOTNET_RUNTIME_ENTERPRISETESTS_ENABLED 1