Fix find for system uptime element

[mayuresh82]

Certain junos platforms with more than 1 RE return the system uptime information in a different structure. Here is an example from a QFX5100:

<rpc-reply xmlns:junos="http://xml.juniper.net/junos/20.2R0/junos">
    <multi-routing-engine-results>

        <multi-routing-engine-item>

            <re-name>localre</re-name>

            <system-uptime-information xmlns="http://xml.juniper.net/junos/20.2R0/junos">
                <current-time>
                    <date-time junos:seconds="1655920775">2022-06-22 10:59:35 PDT</date-time>
                </current-time>
                <time-source> NTP CLOCK </time-source>
                <system-booted-time>
                    <date-time junos:seconds="1639095204">2021-12-09 16:13:24 PST</date-time>
                    <time-length junos:seconds="16825571">27w5d 17:46</time-length>

This change will enable the match for current-time/date-time to work for multi levels deep while still also working for single RE outputs.